= Solution
A <proton> contains <up quarks> on which the <charged current> can act:
$$
\boxed{e^-u\longrightarrow\nu_e d}
$$
through $W^-$ exchange, weighted by $V_{ud}$. Spectator <quarks> complete the hadronic final state. At the exclusive nucleon level the charge assignment is $e^-p\to\nu_e n$; at the high <momentum> transfers specified, the generally dominant description is inclusive $e^-p\to\nu_e X$ with <proton> structure and hadronic breakup, not an unsuppressed pointlike proton-to-neutron transition. The <Quark>[quark-level] diagram in the figure displays this allowed charge flow. The <electron>'s <Chirality>[left-chiral] selection is the same as in part d.
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