\( A, B, C \) are fixed points and \( P \) is a variable point. Resultant of forces \( \overline{P A} \) and \( \overline{P B} \) always passes through \( C \). The locus of point \( P \) is :
(a) A circle centred at mid-point of \( A B \)
(b) A straight line bisecting the angle \( \angle B C A \)
(c) A straight line through \( C \) bisecting \( A B \)
(d) None of the above
