Answer:
C
Explanation:
I know because ¨To begin with¨ sounds better than the rest.
This is the correct answer-- To begin with, his hands and feet are bigger than normal, which helps him move quickly through the water.
This is not-- Finally, his hands and feet are bigger than normal, which helps him move quickly through the water.
Or this--Equally important, his hands and feet are bigger than normal, which helps him move quickly through the water.
And definitely not this--In addition, his hands and feet are bigger than normal, which helps him move quickly through the water.
I am 99.9% sure, but if I am wrong, please correct me.