Could someone me with these two simple science questions real quick? i chose answer c) for both of my answers but i'm not 100% (picture attached)

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen

The negative impacts of nonnative species generally outweigh the positive impacts

Adrought killed all the plants in an agricultural farmland. gradually, due to wind and some birds for. nearby areas, new plants started sprouting l. what stage of succession was taking place in the farmland? a) competition b) nudation c) ecesis d) reaction e) migration