d
\(\begin{array}{l}
Maximum\,percentage\,error\,in\,A\\
= 3\left( {\% \,error\,in\,p} \right) + 2\left( {\% \,error\,in\,Q} \right)\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \frac{1}{2}\left( {\% \,error\,in\,R} \right) + 1\left( {\% \,error\,in\,S} \right)\\
= 3 \times 0.5 + 2 \times 1 = \frac{1}{2} \times 3 + 1 \times 1.5\\
= 1.5 + 2 + 1.5 + 1.5 = 6.5\%
\end{array}\)