Answer: D. To suggest an alternative.
Step-by-step explanation:
Conjunctions are the words that are used in linking other words, clauses or sentences together. Examples of conjunction include or, while, and, since, but, because, nor, yet, although, unless, etc.
"Or"used is used to to link alternatives. It is used for connecting choices or possibilities or choices. In this case, or is used in suggesting an alternative. Therefore, the correct option is D.