An important aspect of fission reactions is that they produce which allow for chain reactions.
a) electrons
b) neutrons
c) protons
d) quarks

B. neutrons

Explanation:

When a free neutron hits the nucleus of a fissile atom like uranium-235 (235U), the uranium splits into two smaller atoms called fission fragments, plus more neutrons. Fission can be self-sustaining because it produces more neutrons with the speed required to cause new fissions. This creates the chain reaction.

B)neutrons

Explanation:

Fission reactions split large nuclei and release neutrons. The released neurons can then split another nucleus and the reaction can continue.