"X is not a positive number."

Hi, I have encountered this kind of quote from different test prep software.
However, there are difference in interpretation.

The possibilities for X are as followed

1.) X is a negative number
2.) X is zero
3.) X is a positive fraction
4.) X is a negative fraction

One test prep assumes only 1.), and 2.)

Another assumes 1.), 2.), 3.), and 4.)

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If I really encounter in the real test, what should I assume?