What do all carbon atoms (and ions) have in common

In which case would a scientist choose to use a dissecting microscope rather than a compound microscope

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons

Whats one way that rocks do not follow the typical rock cycle pathway?