Why Are Uranus and Neptune Less Massive Than Jupiter and Saturn

Why are Uranus and Neptune less massive than Jupiter and Saturn?

A) because they formed before Jupiter and Saturn, when there wasn't enough gas in the solar nebula yet
B) because they formed farther out in the solar nebula, where there was less gas available
C) because they formed very close to the Sun, where intense solar radiation evaporated some of their atmosphere into space
D) because they are composed of mostly ice, and there is less ice farther out in the solar nebula
E) because they formed around a different star, and were captured by the Sun later on.