Vocabulary – Choose the option that best expresses the meaning of the highlighted word in the sentence. Sentence: It is very difficult to “retain” all that you hear in the class.

Introduction / Context:
The sentence discusses memory and learning. The verb “retain” in educational contexts generally means “to keep in memory” rather than “to retrieve” at a later time. We must select the closest meaning among the choices provided.

Given Data / Assumptions:

• Target word: retain (classroom context).
• Sense focus: keeping information stored in memory.
• Options include near-synonyms with slightly different shades.

Concept / Approach:
Differentiate “retain” from “recall.” “Retain” emphasizes storage; “recall” emphasizes retrieval. “Preserve” and “conserve” are more physical or resource-management oriented and are less idiomatic for mental processes. “Keep” maps directly to the idea of continued holding, including in memory, making it the best one-word paraphrase here.

Step-by-Step Solution:

Verification / Alternative check:
Paraphrase: “It is difficult to keep everything you hear in memory.” This preserves the original meaning precisely, confirming “keep.”

Why Other Options Are Wrong:

• recall: Retrieval, not storage; related but not equivalent.
• preserve: Physical maintenance, less natural for memory in this sentence.
• conserve: Saving resources/energy; does not fit the mental lexicon context.

Common Pitfalls:
Learners often conflate memory retention with recall performance. Someone may retain knowledge yet momentarily fail to recall it during a test.

Final Answer:
keep