Select the most appropriate option to fill in the blank.
Famous for being a long distance swimmer, Mihir Sen was the first Asian to swim
__________ the English Channel.

Option B: Correct. Swim "across" the English Channel is correct because, across is the preposition that indicates movement from one side to another, which is what swimming is. Hence, it is the most appropriate.

Preposition "over" refers to movement to a "higher level". Hence, it is not right, since swimming is sideways movement.

Preposition "against" refers to moving opposite something. Like against the river current. Hence, it is not valid here.

Preposition "through" refers to movement from one side to another, in an enclosed space. Since English Channel is not enclosed, hence through is not valid here.