Intersection of Submodules is Submodule

Theorem
Let $R$ be a ring.

Let $\struct {G, +_G}$ be an abelian group.

Let $M = \struct {G, +, \circ}_R$ be an $R$-module.

Let $H$ and $K$ be submodules of $M$.

Then $H \cap K$ is also a submodule of $M$.