What kind of word is the pronoun in bold letters the boy told me that the brown dog was his
subject
direct object
predicate nominative

Predicative nominative

Explanation:

A predicative nominative is a word that renames the subject of a verb. This is always a noun or a pronoun. In this example, the word "his" renames "the brown dog" which is the subject of the verb "was." A predicative nominative can also be a noun phrase and thus be composed of more than one word. Moreover, the verb can also include auxiliary verbs.