The resultant of two vectors \( \mathrm{P} \) and \( \mathrm{Q} \) is \( \mathrm{R} \). If \( \m...

The resultant of two vectors \( \mathrm{P} \) and \( \mathrm{Q} \) is \( \mathrm{R} \). If \( \mathrm{Q} \) is doubled; the new resultant is perpendicular to \( \mathrm{P} \), then \( \mathrm{R} \) equals to:
a. \( P \)
b. Q
c. \( P+Q \)
d. \( P-Q \)