I honestly think it is D. Impulses.
Wind forms when the sun heats up one part of the atmosphere differently that another part.
Answer:
A. Galaxies
Explanation:
Galaxy cluster is known to contains 50 to 1000 galaxies, having a total mass between 100 trillion and 1 quadrillion solar masses, crossing across a distance of 30 million light years.
The word galaxy is derived from the Greek galaxias which means milky, a reference to the Milky Way. Galaxies range in size from the smallest of it with just a few hundred million stars to giants with one hundred trillion stars, with each rotating/orbiting its galaxy's center of mass.
