Final answer:
The reverse quark flavor change u → d does occur in β+ decay, facilitated by the weak force, not the strong nuclear force. The weak force allows for the change in quark flavor, a fundamental aspect of beta decay processes. Therefore, the correct option is c).
Step-by-step explanation:
In the process of beta decay, a neutron in the nucleus of an atom is transformed into a proton, an electron (beta particle), and an electron antineutrino. This transformation involves a change in the flavor of quarks, specifically from a down quark (d) to an up quark (u), facilitated by the weak force. In contrast, beta-plus decay (β+ decay) involves the conversion of a proton into a neutron, a positron (the antimatter counterpart of the electron), and an electron neutrino. During this process, an up quark is changed into a down quark (u → d), again under the influence of the weak force.
The reverse quark flavor change u → d does occur in β+ decay, which is an example of the weak force's ability to change quark flavor, unlike the strong nuclear force which cannot. The weak nuclear force is responsible for processes where not only the down and up quarks can change into each other, but it also allows for changes involving strange quarks, contributing to phenomena like strangeness not being conserved. Given this understanding, the correct option is c) Yes, due to weak force.