A spoon is too big to fit into the keyhole.
This justifies what answer for what question? Q & A: 
One of the following sentences is nonsensical. Which one is it?
Options:
- Sentence A: "he opened his room door with spoon"
- Sentence B: "he opened his room door with key"

Sentence A
A spoon is too big to fit into the keyhole.
This justifies what answer for what question? Q & A: 
user
One of the following sentences is nonsensical. Which one is it?
Options:
- Sentence A: "he opened his room door with spoon"
- Sentence B: "he opened his room door with key"

Sentence A
assistant
A spoon is too big to fit into the keyhole.
This justifies what answer for what question? Q & A: 
One of the following sentences is nonsensical. Which one is it?
Options:
- Sentence A: "he opened his room door with spoon"
- Sentence B: "he opened his room door with key"

Sentence A