Earth is a rocky planet_____ liquid water, which is necessary for life, can exist.

A. as       B. which            C. where          D. when

Earth is a rocky planet _______ liquid water, which is necessary for life, can exist.

   A. as        B. which       C. where      D. when

Earth is a rocky planet _______ liquid water, which is necessary for life, can exist.

   A. as        B. which       C. where      D. when

Earth is a rocky planet_____ liquid water, which is necessary for life, can exist.

A. as       B. which            C. where          D. when

 Earth is a rocky planet______ liquid water, which is necessary for life, can exist.

A. as　 B. where　　 C. which　　　 D. when