plotting - How do I fill in a circle made by ParametricPlot with one solid color?

I have a very simple question but I am new with Mathematica. I made a circle on a parametric plot and I made the line black. I want to make the inside of the circle on the parametric plot red. So the result should be a red-filled circle with a black outline on an x and y axis.

Code:

ParametricPlot[{Cos[u], Sin[u]}, {u, 0, 2 Pi}, PlotStyle -> Black]