Sills usually are fed by dikes, but these may not be exposed in the field. Laccoliths are somewhat large intrusions that result in uplift and folding of the preexisting rocks above the intrusion. They are also concordant types of intrusions. Batholiths are very large intrusive bodies, usually so large that there bottoms are rarely exposed. Sometimes they are composed of several smaller intrusions.
Stocks are smaller bodies that are likely fed from deeper level batholiths.
Stocks may have been feeders for volcanic eruptions, but because large amounts of erosion are required to expose a stock or batholith, the associated volcanic rocks are rarely exposed. Answer - They are exposed by erosion which has removed all of the material above the intrusion.