In which of the reactions represented by the following equations is HNO3 behaving as a typical acid?

A. CaO + 2HNO3 → Ca(NO3)2 + H2O
B. Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2
C. S + 6HNO3 → H2SO4 + 6NO2 + 2H2O
D. P + 5HNO3 → H3PO4 + 5NO2 + H2O

Correct Answer: Option A

A. CaO + 2HNO3 → Ca(NO3)2 + H2O