A.I. Explanation:

Correct answer: conducted

Explanation: The verb 'conducted' is the past tense of 'conduct,' which is appropriate here as it indicates that the researchers carried out an experiment. This fits grammatically as it aligns with the past tense narrative of the sentence.

Meaning: 'Conducted' means to carry out or perform an activity, in this case, an experiment.

Wrong options:

• dangle: The verb 'dangle' means to hang loosely, which does not relate to the action of performing an experiment.
• tramp: The verb 'tramp' means to walk heavily or noisily, which is irrelevant in the context of conducting research.
• abruptly: The adverb 'abruptly' describes a sudden action, but it does not fit as a verb to describe the researchers' actions.
• sustained: The verb 'sustained' means to maintain or support, which does not apply to the action of conducting an experiment.

Correct answer: cruise

Explanation: The verb 'cruise' fits contextually as it describes the action of driving at a constant speed, which is what the drivers were instructed to do. It maintains grammatical consistency with the infinitive form following 'to.'

Meaning: 'Cruise' means to travel smoothly at a steady speed, particularly in a vehicle.

Wrong options:

• dangle: The verb 'dangle' does not relate to driving and implies hanging, which is not applicable here.
• tramp: The verb 'tramp' refers to walking heavily, which does not fit the context of driving vehicles.
• abruptly: The adverb 'abruptly' indicates a sudden change, which contradicts the idea of maintaining a constant speed.
• sustained: The verb 'sustained' does not fit as it implies maintaining something rather than the action of driving.

Correct answer: smoothly

Explanation: The adverb 'smoothly' describes how the traffic moves, indicating that it is flowing without interruptions. This fits grammatically as it modifies the verb 'moves' appropriately.

Meaning: 'Smoothly' means in a steady and even manner, without bumps or interruptions.

Wrong options:

• dangle: The verb 'dangle' does not fit as it does not describe the manner of movement.
• tramp: The verb 'tramp' is unrelated to the context of traffic movement and implies heavy walking.
• abruptly: The adverb 'abruptly' suggests a sudden change, which contradicts the idea of smooth movement.
• sustained: The verb 'sustained' does not apply as it does not describe the manner of movement.

Correct answer: spread

Explanation: The verb 'spread' is appropriate here as it describes how the traffic jams extend backwards. It fits grammatically and contextually, indicating the action of the jams moving in a specific direction.

Meaning: 'Spread' means to extend over a larger area or to move outwards.

Wrong options:

• dangle: The verb 'dangle' does not relate to the movement of traffic jams and implies hanging, which is not applicable.
• tramp: The verb 'tramp' refers to walking heavily, which does not fit the context of traffic movement.
• abruptly: The adverb 'abruptly' suggests a sudden action, which does not describe the gradual nature of how jams spread.
• sustained: The verb 'sustained' does not apply as it implies maintaining rather than the action of spreading.