Which sentence expresses a future ability that is unlikely due to sickness?

• A. He will be unable to attend the meeting.
• B. He is unable to attend the meeting.
• C. He would be unable to attend the meeting.
• D. He could be unable to attend the meeting.

Answer: (A)

The main concept here is choosing the verb form that shows a definite future state, specifically a future inability caused by a sickness. Saying someone “will be unable to attend” reports a future situation where attendance will not be possible, which matches a future inability due to illness. The present tense version describes a current inability, not something that will happen later. The conditional form suggests a hypothetical or less certain situation, not a definite future fact. The modal “could be” expresses possibility rather than a definite future outcome. So the sentence with will be unable to attend the meeting best conveys a future inability due to sickness.