The First Stars Formed About 300 Million Years After Big

The first stars formed about 300 million years after Big Bang in the most massive nebulae because___________ .

A) all of the nebulae at that time were massive and it was not until much later that smaller nebulae formed
B) the massive nebulae had enough gravity to collapse and condense
C) only the massive nebulae had the material needed to make stars
D) the massive nebulae had enough gravity to attract star material early in the history of the universe
E) it took that long for enough matter to form to make a star