If he were here, it could be more fun.

Analyze the question: The sentence "If he were here, it could be more fun" is a second (unreal) conditional. It talks about a situation that is contrary to fact: he is not here, so there is less fun than there would be.

Concept: The subjunctive "were" in an if-clause (If he were...) signals an imaginary or untrue present situation. It means the opposite is true:

• "If he were here" → he is not here.
• "it could be more fun" → it is not as much fun now.

Evaluate the options:

• A. "He was expected but did not show up to make the occasion lively." The sentence never says he was expected. It only says he is absent and that his presence would add fun. This adds information that is not given.
• B. "There was no fun because he was not present." This is too strong. The sentence says there would be more fun, not that there was no fun.
• C. "He did not show up so the occasion lacked much fun." This matches: he is absent (contrary to fact), and the occasion has less fun than it could have. "Lacked much fun" fits "more fun" if he were present.
• D. "He was being expected to supply more fun." This misreads the sentence completely. It is not about an expectation or duty.

Answer: The best explanation is C. It captures both the absence and the reduced (not zero) level of fun, without adding unstated details.

Tip: For "If + were/had..." sentences, flip the meaning. If the sentence says "If he were here," think "he is NOT here." Also watch out for extreme words like "no fun" and for options that add facts not in the sentence, such as "he was expected."