I recently had this question in a quiz and was quite confused as I don't think I can assume there are more zeros from just one, so how should I interpret it?

Assuming a linear phase FIR filter with real value coefficients and a zero at $2e^{j0.5\pi}$, which of these is true?

a)There are another 3 zeros at $2e^{-j0.5\pi}$ , $0.5e^{j0.5\pi}$ and $0.5e^{-j0.5\pi}$ 


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b)There are more than 3 other zeros.


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c)Theres just another zero at $2e^{-j0.5\pi}$


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d)All the zeros in the filter are within the unit circle

Thank you