AMC 12 2019a Problem 2

Suppose $a$ is $150\%$ of $b$. What percent of $a$ is $3b$?

$\textbf{(A) } 50 \textbf{(B) } 66+\frac{2}{3} \textbf{(C) } 150 \textbf{(D) } 200 \textbf{(E) } 450$