Lady Montagu introduced the smallpox inoculation to Europe. (add a prepositional phrase)

Lady Montagu introduced the inoculation of smallpox to Europe.

Explanation:

A prepositional phrase is a group of words that consists of a preposition, its object, and the words that modify the object. Prepositions are words used to connect other words within a sentence and express the relationship between them (e.g. space and time).

In the given sentence, a prepositional phrase can be introduced by changing the words smallpox inoculation into inoculation of smallpox. The preposition here is of and its object is smallpox.