A.I. Explanation:

Option 1: "They are too difficult for students to do"

Explanation: The text does not state that dissertations are too difficult for students. Instead, it highlights that students struggle to find suitable topics and may need to refine their proposals, which does not equate to the overall difficulty of the dissertation itself.

Option 2: "The subject area selected may not have sufficient focus"

Explanation: The speaker mentions that students often choose topics that are too broad and need to be refined, indicating that the subject area may lack sufficient focus. This aligns directly with the main idea of the text, which discusses the challenges students face in selecting appropriate dissertation topics.

Option 3: "There is a lack of understanding of how to conduct research"

Explanation: While the speaker notes that students may struggle with their dissertation topics, there is no mention of a lack of understanding of research methods as a general issue. The focus is more on topic selection rather than research methodology.

Option 4: "Students will not be allowed to alter their proposed topic"

Explanation: The speaker explicitly states that modifications to the proposal are expected as the work progresses, indicating that students are indeed allowed to alter their proposed topics, contrary to what this option suggests.