The correct answer is: Alkaline metals.
Hydrogen has one electron in its valence shell, which is the outermost shell of an atom. Alkaline metals also have one electron in their valence shell. This means that hydrogen and alkaline metals have similar chemical properties. For example, both hydrogen and alkaline metals are very reactive and can easily form bonds with other elements.
Alkaline earth metals have two electrons in their valence shell. Inert gases have eight electrons in their valence shell. Halogens have seven electrons in their valence shell.
Here is a table showing the electron configuration of each of the elements mentioned in the question:
Element | Electron configuration
——- | ——–
Hydrogen | 1s1
Alkaline metals | ns1
Alkaline earth metals | ns2
Inert gases | ns2np6
Halogens | ns2np5
As you can see, hydrogen has the same electron configuration as the alkaline metals. This is why hydrogen is often classified as an alkali metal.