This seems to be specific to the CFA exam and is a badly formulated question. First, an indifference curve for some fixed utility level can be viewed as a function mapping $\sigma$ to $\mu$. At any value of $\sigma$, this function has a slope (which is given by $\sigma A$). No economist would call this a "slope coefficient" in this context, as this ...
It would seem that both options are correct given the specific mean-variance utility function.
Use $\mu$ to denote the expected value. In the $(\sigma,\mu)$-plain, an indifference curve representing a particular utility level $\overline U$ is given by
\overline U=\mu-\frac12 A\sigma^2.
Applying implicit differentiation, we can ...