#### Answer

B

#### Work Step by Step

In the standard equation $y=a \sin bx$, $a$ is the amplitude while $b$ can be used to find the period. In the equation $y=4 \sin 2x$, $a=4$ while $b=2$.
Since $a=4$, this means that the amplitude is 4.
Now we use $b$ to find the period using the formula:
Step 1: Period$=\frac{2\pi}{b}$
Step 2: Period$=\frac{2\pi}{2}$
Step 3: Period$=\pi$
Therefore, we know that the amplitude is 4 while the period is $\pi$. This means that Option B is true.