They are crossing the membrane so
JSIOWWHEIOWOWWbrainly
The cell has to use active transport when it's trying to transport material against the concentration gradient. (from low to high concentration) Or, if a molecule is too big to diffuse through the cell membrane, it must be moved through using a carrier protein.
Hope that helped you.
The answer is (b) hope it helps have a good day :)
If it is the temperature or something like that, maybe yes. It depends.
This is in cellular respiration I believe, where glucose is broken into pyruvate. This is done in the cytoplasm especially in the cytosol.