Researchers are experimenting with various techniques
for preventing the accumulation in water of high levels
of nitrogen, which can kill plants and animals.
(A) nitrogen, which can kill plants and animals
(B) nitrogen; plants and animals can be killed
(C) nitrogen, that is what can kill plants and animals
(D) nitrogen, they could kill plants and animals
(E) nitrogen, and they can kill plants and animals
Who are Researchers?