Up to the present time, oceanographers ____ lots of seafloor mountains they ___

Up to the present time, oceanographers ____ lots of seafloor mountains they ____ existed.

A were finding/ don't know

B have found / haven't know

C are finding / don't know

D will find / wouldn't know

Correct Answer: Option B

বাক্যে Up to the present time থাকায় বাক্যটি Present perfect tense হবে।