Immigration currently accounts for about of u. s. population growth.
a. one-half
b. a quarter
c. one-third
d. three-quarters

According to government statistics the current immigration accounts to 13,3% of the population. Therefore none of the answers is correct.

Hope this helps.

The answer is b im not sure 

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.