C

 careful (adj) 

A: Careful but you are going to wake her up.

B: This one well did not wake up.

ceiling (n)

A:The ceiling is going to fall watch out!

B: Run for his life!

century (n)

A:This century is better than the previous one

B: It is true.

chain (n)

A: The chain of the thieves broke now they are free, have a lot of care !

B: Ok .

crossing (n) 

A: Use the crossing to cross the street.

B: Ok.