Which statement about the circumference (perimeter) of an ellipse is correct?

The circumference is exactly $2\pi \sqrt{(a^2+b^2)}$ for every ellipse.

The circumference is exactly $\text{𝜋}(𝑎+𝑏)$ for every ellipse, matching the circle formula when $𝑎=𝑏$.

There is no standard, simple equation to find the exact circumference of an ellipse using basic algebra.

The circumference equals $2\pi ab$, analogous to the circle formula $2\pi r$.