Which explains how the moon causes low tides on the earth?

a.
the moon exerts a gravitational pull on the earth. the pull stretches the earth's watery envelope and creates tidal bulges. where the water bulges out is low tide.

b.
the moon's gravity pushes on the earth. the push indents the earth's watery envelope and creates tidal bulges. where the water is pushed in is low tide.

c.
the moon exerts pull on the earth. the pull stretches the earth's watery envelope and creates tidal bulges. where the water is thinnest is low tide.

d.
the moon's gravity pushes on the earth. the push indents the earth's watery envelope and creates tidal bulges. where the water is pushed out is low tide.