C. The nervous system sends signals to make muscles move.
C. The problem of endangered species
Sex is a reproduction system involving both male and female to partake in sexual activity intercourse to create an offspring between the two beings creating a living organism
D - birth control is the most widely accepted method
There are a few vital characteristics to mention here. First we have to know about which ions we're talking about as the cellular membrane is semi-permeable (lets some flow freely through the membrane and some not), it depends on the size of the compounds, and also the charge that a molecule has.