Answer:
But
Explanation:
A coordinating conjunction is a word placed or used to connect words, phrases, clauses or sentences examples of such words are : but, and, or, nor, else, so and yet.
In the above sentences Derek came to the party but Susan stayed home the coordinating conjunction but have been able to connect the two sentences Derek came to the party with Susan stayed at home as one whole sentence.
Derek is a noun in the sentence because it represents the name of a person while home is also a noun because it represents the name of place as well
