Let `P-= (a,b), Q-=(c, d) and 0ltaltbltcltd, L-=(a,0), M-=(c, 0), R` lies on x-axis such that `PR=RQ` is minimum, then `R` divides `LM` (A) internally in the ration `a:b` (B) internally in the ration `b:c` (C) internally in the ration `b:d` (D) internally in the ratio `d:b`