Which is a run-on sentence?

A.
The squirrel ran across the yard it climbed up the tree.

B.
The hamster likes his wheel, but he spins in it all night long.

C.
The duck waddled up the embankment, and it quacked at me.

D.
The fox sat in the middle of the yard, and it stared at us.

Question

Which is a run-on sentence?	
 
 A.
The squirrel ran across the yard it climbed up the tree.
 
 B.
The hamster likes his wheel, but he spins in it all night long.
 
 C.
The duck waddled up the embankment, and it quacked at me.
 
 D.
The fox sat in the middle of the yard, and it stared at us.

anonymous · Answer

an can u explain why.

anonymous · Answer

A.) The squirrel ran across the yard it climbed up the tree. 
This is correct because there is no comma or FANBOY to make it correct.