Solution
= Solution
Under <charge conjugation>, $\phi\leftrightarrow\phi^*$ must be accompanied by
$$
A_\mu\mapsto-A_\mu.
$$
Then $D_\mu\phi$ is exchanged with $(D_\mu\phi)^*$, while $F_{\mu\nu}\mapsto-F_{\mu\nu}$. The scalar kinetic and mass terms are therefore exchanged with themselves and $F_{\mu\nu}F^{\mu\nu}$ is unchanged, proving invariance of <scalar quantum electrodynamics>.