#### Answer

$\pi t+C$

#### Work Step by Step

$\int \pi dt = \pi \int dt$ (constant is taken out)
= $\pi\times t+C$ (As $\int dt= t+constant$)
= $\pi t+C$
Now, $\frac{d}{dx}(\pi t+C)= \frac{d}{dx}\pi t + \frac{d}{dx}C = \pi +0 = \pi$
Here, derivative of the integral is the integrand. So the answer is correct.