Consider a matrix \(M \in \mathbb{R}^{3 \times 3}\) and let \(U\) be a 2-dimensional subspace such that \(M\) is a projection onto \(U\). Which of the following statements are true?
- \(M^3 = M\)
- \(M^2 = M\)
- The nullspace of \(M\) is 1-dimensional.
- The nullspace of \(M\) is 2-dimensional.