Which body system's main function is to send and receive impulses to direct body activities?

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the answers are a and c

idk what happened..you tell

answer///(c) the maximum number of organisms an environment can support for a long time; i believe this is correct, plz check luck;