A.I. Explanation:

Correct answer: infectious

Explanation: The word 'infectious' fits grammatically as it describes the type of bacteria that antibiotics target. It aligns with the context of the sentence, which discusses how antibiotics eliminate harmful bacteria.

Meaning: 'Infectious' refers to bacteria that can cause disease and spread from one person to another.

Wrong options:

• zealous: 'Zealous' means showing great energy or enthusiasm, which does not relate to the type of bacteria being discussed.
• vulnerable: 'Vulnerable' means susceptible to harm, but it does not accurately describe the bacteria that antibiotics are designed to eliminate.
• capricious: 'Capricious' means given to sudden changes in mood or behavior, which is irrelevant in the context of bacteria and antibiotics.

Correct answer: mutating

Explanation: The word 'mutating' is the correct choice as it describes the process by which bacteria change to resist antibiotics. This fits both grammatically and contextually within the sentence.

Meaning: 'Mutating' means undergoing a change, particularly in genetic structure, which allows bacteria to adapt and survive against antibiotics.

Wrong options:

• retaining: 'Retaining' means keeping or holding onto something, which does not convey the idea of bacteria changing to resist drugs.
• commuting: 'Commuting' refers to traveling back and forth, which is unrelated to the context of bacterial resistance.
• upset: 'Upset' means to disturb or displace, which does not fit the context of bacteria adapting to antibiotics.

Correct answer: different

Explanation: The word 'different' is appropriate as it indicates that the bacteria may become vulnerable to another type of drug. This fits grammatically and contextually within the sentence.

Meaning: 'Different' means not the same as another or others, highlighting the potential for bacteria to be susceptible to an alternative antibiotic.

Wrong options:

• referenced: 'Referenced' means mentioned or cited, which does not fit the context of discussing types of drugs.
• interfaced: 'Interfaced' refers to connecting or interacting, which is not relevant in this context.
• dissimulating: 'Dissimulating' means concealing or disguising one's thoughts or feelings, which does not apply to the discussion of drug susceptibility.

Correct answer: knockout

Explanation: The word 'knockout' fits well as it conveys the idea of delivering a decisive blow to the bacteria, aligning with the context of the sentence about combating antibiotic resistance.

Meaning: 'Knockout' refers to a powerful blow that incapacitates or defeats, particularly in a competitive context.

Wrong options:

• ragout: 'Ragout' is a type of stew, which is irrelevant in the context of discussing antibiotics and bacteria.
• layoff: 'Layoff' refers to dismissing employees from their jobs, which does not relate to the context of fighting bacteria.
• sought: 'Sought' is the past tense of seek, meaning to look for, which does not fit the context of delivering a blow.

Correct answer: susceptible

Explanation: The word 'susceptible' is the correct choice as it describes bacteria that have become more vulnerable to a second drug after mutation. This fits grammatically and contextually.

Meaning: 'Susceptible' means likely to be influenced or harmed by a particular thing, indicating the bacteria's increased vulnerability.

Wrong options:

• sustainable: 'Sustainable' refers to the ability to be maintained or continued, which does not apply to the context of bacterial resistance.
• liable: 'Liable' means likely to do or experience something, but it does not convey the specific vulnerability of bacteria to drugs.
• dependent: 'Dependent' means relying on something else, which does not accurately describe the relationship between bacteria and antibiotic resistance.