CAT 2019 Trigonometry — Previous Year Question

Let $ABC$ be an isosceles triangle. Suppose that the sides $AB$ and $AC$ are equal and let the length of $AB$ be $x$ cm. Let $b$ denote the angle $\angle ABC$ and $\sin b = 3/5$. If the area of the triangle $ABC$ is $M$ square cm, then which of the following is true about $M$?