Which of these poisons a friendship the worst?

Just reverse the gender roles if you're a guy.
Jealousy (your friend thinks you're prettier/smarter/more popular)
Vote A
Talking behind each other's backs
Vote B
Crushing on/flirting/getting with each other's boyfriends
Vote C
Thinking your friend is doing something you find morally repugnant
Vote D
Competition at school or work
Vote E
Other
Vote F
Select age and gender to cast your vote:
GirlGuy
Which of these poisons a friendship the worst?
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