Which of the following are the elements in the sulfhydryl group? A.

hydrogen and sulfur

B.

carbon, hydrogen, and sulfur

C.

carbon, hydrogen, sulfur and nitrogen

Which would best keep the oxygen cycle stable? a. cutting down jungles to create farmland b. eliminating parks in large cities c. dumping toxic chemicals into the ocean d. reducing the amount of deforestation d. reducing the amount of deforestation

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic