Explanation:
The correct answer is option B: Preposition.

A preposition is a word that shows the relationship of a noun or pronoun to another word in the sentence. In this case, the word "to" is a preposition that shows the relationship between the verb "invite" and the noun "Italy."

Why it is not a conjunction:
A conjunction is a word that connects words, phrases, or clauses. It is used to coordinate or join words or groups of words together. In the given sentence, "to" does not connect two clauses or phrases. Instead, it establishes the relationship between the verb and the noun, making it a preposition rather than a conjunction.

Usage of prepositions:
Prepositions are commonly used to indicate direction, location, time, manner, and other relationships. They can be used to show where something is, when something happened, how something is done, and so on. In this case, the preposition "to" is used to indicate the destination or location that the speaker has been invited to, which is Italy.

Example of prepositions:
Here are some examples of prepositions used in sentences:

- I went to the store.
- The book is on the table.
- She walked through the park.
- He arrived at the party.

In each of these sentences, the preposition shows the relationship between the noun or pronoun and another word in the sentence.

Conclusion:
In the given sentence, "to" is a preposition that shows the relationship between the verb "invite" and the noun "Italy." It indicates the location or destination of the invitation.