Under Hardy-Weinberg assumptions, a diploid population has genotype frequencies $f_{AA}$, $f_{Aa}$, and $f_{aa}$. Which expression correctly calculates the allele frequency of $A$ (i.e., $p$) from these genotype frequencies?

• A. $p=1-f_{AA}$
• B. $p=f_{AA}+f_{Aa}$
• C. $p=f_{AA}+\frac{f_{Aa}}{2}$
• D. $p=\frac{f_{AA}+f_{Aa}}{2}$

Answer: (C)