An Ideal 100- $\mathrm { V }$ Dc Battery Is Applied Across a Series Combination of Four

An ideal 100- $\mathrm { V }$ dc battery is applied across a series combination of four resistors having resistances of $20 \Omega , 40 \Omega , 60 \Omega$ , and $80 \Omega$ . What is the potential difference across the $40 - \Omega$ resistor?

A) $60 \mathrm {~V}$
B) $100 \mathrm {~V}$
C) $40 \mathrm {~V}$
D) $20 \mathrm {~V}$
E) $80 \mathrm {~V}$