Someone please help asap.

B

Explanation:

All animals in the food chain have a job and keep each other balanced.  With out the top predator the species that are lower than the top predator will over populate and throw off the food chain.

Hope this helps :)

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.