The plasma membrane is a special cellular structure that can be found in animals and plants that has the sole role of keeping things together and preventing things from coming in. For these two reasons, it's an important player in homeostasis.
A. dust.I don't think that dust could be a hazard to your head :)
Work out and try to eat protein such as meat
C. maintain a regular exercise program
I’m pretty sure the answer is A, more energy consumption than you’re spending would generally cause weight gain