Question

____ he is ninety years old , he is in the pink of health​

Answer 1

Answer:

though

Explanation:

He's ninty years old though he's in the pink of health.

Answer 2

Although he is ninety years old , he is in the pink of health​. -this is the answer.

About filling in the blank:

• There is blank which has to be filled in with appropriate word.
• As we see that "he is ninety years old" and "he is in the pink of health​" are two clauses, we need to join them using a conjunction.
• Conjunctions are linking words. That is they are words that help to join  two clauses/ phrases/ words.
• Some of the conjunctions are: because, even though, so that, so-that, yet, but, still, etc.,
• The first half of the sentence says that he is ninety years old. But the second half says that he is healthy. So it is contradiction. Thus we have to use conjunctions like 'though/ although/ even though'.
• Therefore the answer is: Although/ Even though.