The presence of which of the following substances can allow a chain reaction to happen?
a) a reactive product
b) a reactive intermediate
c) a beta particle
d) none of the above

im not sure either B or D b is the only one with evidence

Explanation:

Most chemical chain reactions have very reactive intermediates called free radicals. The intermediate that maintains the chain reaction is called a chain carrier. These atoms or fragments are usually derived from stable molecules due to photo- or heat-dissociation

tracks, burrows, eggshells, nests, tooth marks, or gastroliths