Here's why:

* Covalent bonds involve the sharing of electrons between atoms.

* Carbon (C) has 4 valence electrons, and hydrogen (H) has 1 valence electron.

* In methane, each hydrogen atom shares one electron with the carbon atom, forming a single covalent bond.

* This results in a stable molecule where the carbon atom has a full outer shell of 8 electrons and each hydrogen atom has a full outer shell of 2 electrons.