Final answer:
Electrons are the subatomic particles that play the most active role in chemical bonding, as they are involved in interactions between atoms.
Step-by-step explanation:
Electrons play the most active role in chemical bonding. Atoms consist of a nucleus containing protons and neutrons, with electrons orbiting this central nucleus. The negatively-charged electrons interact with other atoms' electrons to form chemical bonds. Each element's number of protons defines its identity, while neutrons contribute to the atom's mass and influence its isotopes. The mass of an electron is approximately 1/2000th that of a proton or neutron. As electrons are much less massive and are located in the outer part of the atom, they are involved in chemical reactions, while the protons and neutrons in the nucleus do not ordinarily play a direct role in these processes. Therefore, the answer to the question is (a) electrons.