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Suppose that $M$ is an $n\times n$ matrix. Which of the following statements are true about the number of eigenvalues $M$ has? Select ALL that apply.

$M$ has infinitely many eigenvalues.

It is possible but not necessary that $M$ has infinitely many eigenvalues

$M$ must have at least one eigenvalue.

$M$ has at most $n$ eigenvalues

None of the above.