When the Solar System Was Forming, the Building Blocks from Which

Multiple Choice

When the solar system was forming, the building blocks from which the protoplanets gathered together were the:

A) gold, iron, and nickel atoms
B) planetesimals (a few km to tens of km wide)
C) giant accretion grains about the size of Mars
D) extremely hot clouds of gas torn out of the Sun, which was already shining brilliantly
E) pure water ice crystals, about the size of a snowflake