A compound sentence is made up of two or more independent clauses joined by a conjunction.
Looking at the options:
A) "I would luv 2 have tacos 4 dinner dis evening." - This is a simple sentence (one independent clause).
B) "Bc she studied hard, angels got an A on her test, n she was so happy." - This sentence has multiple clauses but is not structured correctly as a compound sentence.
C) "AJ worked hard on dis science fair project, yet he did not finished first." - This is a compound sentence because it has two independent clauses: "AJ worked hard on dis science fair project" and "he did not finished first," connected by the conjunction "yet."
D) "After Brian came in second place, he began practicing more." - This is a complex sentence because it contains an independent clause and a dependent clause.
Therefore, the correct answer is C: "AJ worked hard on dis science fair project, yet he did not finished first."