7. For a geometric sequence $\{a_n\}$ with common ratio $q$ and sum of the first $n$ terms $S_n$, let Proposition A: $q > 0$. Proposition B: $\{S_n\}$ is an increasing sequence. Then
A. A is a sufficient but not necessary condition for B
B. A is a necessary but not sufficient condition for B
C. A is a necessary and sufficient condition for B
D. A is neither a sufficient nor a necessary condition for B