Question

The leader spoke boldly __ the reforms

Answer 1

HI! ☺
the answer is:
to

Answer 2

The leader spoke boldly  to__ the reforms.

A preposition is a word, for example, after, in, to, on, and with.

Preposition are generally utilized before things or pronouns and they demonstrate the connection between the thing or pronoun and different words in a sentence.

Example for We sat next to each other.  

If to is followed by a noun construction, it is a preposition.