Who did people rely on for protection during the middle ages?

The king awarded land grants, called fiefs, to the nobles and sometimes to the church in return for the use of their soldiers or their influence on the citizens to protect the land.

assuming the underlined word is "regnant", the correct answer is b) ruling.

basic principle: a pronoun usually refers to something earlier in the text (its antecedent) and must agree in number — singular/plural — with the thing to which it refers. the indefinite pronouns anyone, anybody, everyone, everybody, someone, somebody, no one, and nobody are always singular.