B. Yard
the other answers C. & D. are metric A is a unit of temperature
The correct answer:
nebular theory
The explanation:
-The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems).
-According to the nebular hypothesis, stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC). These clouds are gravitationally unstable, and matter coalesces within them to smaller denser clumps, which then rotate, collapse, and form stars. Star formation is a complex process, which always produces a gaseous protoplanetary disk, proplyd, around the young star. This may give birth to planets in certain circumstances, which are not well known.
-the Big bang theory is about the origin of the universe
- and condensation theory relates to the formation of the Moon and the Earth.
