Which sentence uses the word diaphanous correctly?

Question 5 options:

His brash, diaphanous tone made his uncertainty clear.


Whoever judges the acting competition has to remain diaphanous and consider everyone fairly.


I have no idea who he is; he must be diaphanous.


Even though her mother shut them, Mary could see right through the diaphanous drapes to see what they were attempting to hide from her outside.