The man is either posing for a photo or riding a donkey.
This justifies what answer for what question? Q & A: 
Given the sentence "A man in a hat is posing for a photo with a white donkey pulling a wagon." is it true that "A man in a hat is riding a donkey to mexico."?
no
The man is either posing for a photo or riding a donkey.
This justifies what answer for what question? Q & A: 
user
Given the sentence "A man in a hat is posing for a photo with a white donkey pulling a wagon." is it true that "A man in a hat is riding a donkey to mexico."?
no
assistant
The man is either posing for a photo or riding a donkey.
This justifies what answer for what question? Q & A: 
Given the sentence "A man in a hat is posing for a photo with a white donkey pulling a wagon." is it true that "A man in a hat is riding a donkey to mexico."?
no