Which property of the early solar nebula controlled the formation and positioning of the terrestial planets?

A) I'd also pick this option

B,C) presumable the distribution of hydrogen and silicates was originally uniform in the nebula.

D) this difference only started to occur when the sun began to shine. The inner planets then lost their more volatile components (eg H & He)

I would choose D)

Although it is a very bad question. It either came from some ancient text dating from the Laplacian era, or was put together by someone who was either drunk, knew little science, or probably both.

The distribution of H & silicates would be even until solar output increased at which time the distributions would change, as gaseous H would be driven away from the sun, and particulate silicates would need to vapourize first.

The rotation of the nebula would definitely exert some control, but the eventual orbital positions of the planets depends strongly upon coupling between the nebula and the developing sun, which is very poorly understood at present.

In fact we know very little about the formation of planetary systems. It is actually far more complex than most pundits think it is. The Kepler mission has provided a wealth of data on planetary systems, yet is probably only the tip of the capsizing iceberg. Theory is struggling to keep up with this data.

Cheers!