Kids Riddles

Question: There are two sisters: one gives birth to the other and she, in turn, gives birth to the first. Who are the two sisters?

Question: Imagine you are swimming in the ocean and a bunch of hungry sharks surround you. How do you get out alive?

Question: Which Boston Red Sox player wears the biggest hat?

Question: You throw away the outside, eat the inside, and throw away the inside.

Question: Filled with garb,
the price is free.
Just return what you don't need.

What am I?