A resistor R is connected to a parallel combination of two identical batteries each with emf E and an internal resistance r. The potential drop across the resistance R is

A

$$\frac{2ER}{2R + r}$$

B

$$\frac{ER}{2R + r}$$

C

$$\frac{ER}{R + 2r}$$

D

$$\frac{2ER}{R + 2r}$$