How does sleet form? answer right away

a.
raindrops freeze on their way down to earth.

b.
tiny water droplets collide and form larger drops that fall to the ground.

c.
water vapor freezes into crystals.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.