Why is one of the following always true in a given matrix A?

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Consider A, a given matrix. I want to show that exactly one of the following holds:

1) $\exists x\neq 0$ such that $Ax=0$

2) $\exists p$ such that $p^TA>0$

I tried proving that this is equivalent to Farkas' Lemma, but I couldn't really get anywhere. I also tried writing an LP problem and its dual to see if I get somewhere, but I don't know what to use as the vector in my objective function.