Answer:
Preposition
Step-by-step explanation:
A preposition is used to show the relationship between a noun and a pronoun in a sentence and it is a word that comes after or before a noun or a pronoun and shows a relationship between another word. Some examples of a preposition are at, for, in, on, over, under, etc.
The sentence in question is Waking up on a holiday to the smell of a favorite treat is always wonderful.