In an electric circuit, two resistors with resistances x and y are connected in parallel. If R is the combined resistance of these two resistors, then the reciprocal of R is equal to the sum of the reciprocals of x and y. What is R if x is 3 Ohms and y is 5 Ohms?	Options:
A) 15 / 8 B) 3 / 8 C) 5 / 8 D) 7 / 15 E) 8 / 15

Rationale: "1 / r = 1 / x + 1 / y 1 / r = 1 / 3 + 1 / 5 = 8 / 15 r = 15 / 8 the answer is a ."
Answer: A