Question

5. The driver was wondering (whose, who's) suitcase that was.​

Answer 1

whose would be the correct answer, ...who's is the possesive form for "who is", which would be incorrect if inserted in the sentence

Step-by-step explanation:

Answer 2

Answer: The driver was wondering whose suitcase that was.

Explanation: Who's stands for who is, so if we used who's it would be: The driver was wondering (who is) suitcase that was.

Therefore, the answer is whose...I hope this helps!