If someone has no way to make money but to sell his own labor, then he must be a member of what social group?

If someone has no way to make money but to sell his own labor, he must be a member of: the proletariat

The proletariat is the group within a capitalist society that contribute the most labors and do not possess any significant things other than those labors. Even though they're the backbone of every capitalist society, they tend to be placed on lower economic bracket