An estuary is an area at the mouth of a river where the river joins a sea. Estuaries contain brackish water, which is a mixture of fresh water and salt water. They are rich in nutrients and support a large number of fish species.
The biodiversity of a particular estuary has decreased due to human activities such as pollution, overfishing, and
construction. A scientist wants to develop a method to restore the biodiversity of this estuary. Which method should
the scientist choose?

i think that d. wind is the answer.   i missed the question when i answered a. currents.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

looks like the answer is     c     to me!

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.