= Solution
{c}
Assume (b). A <coproduct in a category> of <monofunctors> in $[\mathcal C,\mathbf{Set}]$ is again a <monofunctor>: at an object it is the disjoint union of the values, and every arrow acts within the same summand by an <injective function>. Distinct summands cannot become identified, and injectivity within a summand follows from its <monofunctor> property.
Apply this to the coproduct of <representable functors> constructed in part (a). Its canonical map to $F$ is a <pointwise epimorphism in a functor category>. Thus every $F$ is an epimorphic image of a <monofunctor>, proving
$$
\boxed{\text{(b)}\Longrightarrow\text{(c)}.}
$$
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