Here's why:

* Electronegativity: Selenium and bromine are both nonmetals. Nonmetals have relatively high electronegativity, meaning they have a strong attraction for electrons.

* Sharing Electrons: In a covalent bond, atoms share electrons to achieve a stable electron configuration. Since selenium and bromine have similar electronegativity values, they share electrons rather than one atom completely taking an electron from the other (which is characteristic of ionic bonding).

Therefore, the bond between selenium and bromine is a covalent bond.