Quark changes depend on decay type, but J is undefined

Steps:

• Identify the decay: Unstable nucleus emits "J", likely a particle like beta (electron), but J unspecified.
• Recall quark content: Nucleus protons (uud), neutrons (udd); decays alter flavors via weak force.
• For beta minus (n → p + e + ν-bar), udd → uud, so +1 up quark, -1 down quark in nucleus.
• Options don't match standard; ambiguity in "J" prevents precise determination.

Why B is correct:

• Not enough information on J to confirm, but if J implies a decay adding an up quark without down change (non-standard), B fits by definition.

Why the others are wrong:

• A: -0 for down is unclear notation, not standard change.
• C: Matches beta plus decay (p → n), opposite for typical unstable nuclei.
• D: Implies only down increase, like inverse beta, not emission of J.

Final answer: Not enough information.