Which is a run-on sentence?

A.
Keys are made for each lock, yet many keys look the same.

B.
Sailboats use wind power, but many sailboats also have a motor.

C.
Flamingos are usually pink one variety is bright red.

D.
Apples are generally red, but there are some golden varieties.

Question

Which is a run-on sentence?	
 
 A.
Keys are made for each lock, yet many keys look the same.
 
 B.
Sailboats use wind power, but many sailboats also have a motor.
 
 C.
Flamingos are usually pink one variety is bright red.
 
 D.
Apples are generally red, but there are some golden varieties.

anonymous · Answer

I'm very sorry if I am wrong but I believe it is C because there is no comma connecting it :)

conqueror · Answer

Direct answers are illegal.

anonymous · Answer

Yeah, C. It doesn't make sense without a comma or full stop, so it's a run-on.