Which sentence is a complex sentence?
O
If you are attending the Fourth of July celebration, I suggest you wear the red, white, and blue shoes
The red, white, and blue shoes are perfect for the Fourth of July celebration.
I would suggest the red, white, and blue shoes, they are perfect for the Fourth of July celebration
If you are attending the Fourth of July celebration, I suggest you wear the red, white, and blue shoes, you will definitely
win the contest.

The first sentence

Explanation:

Simply put, a complex sentence is one in which you have an independent clause and a dependent (subordinating) clause.

Sentence 2 is a simple sentence. (one independent clause)

Sentence 3 is an attempt at a compound sentence (two independent clauses), but it fails because it contains a comma splice. (which is not the correct way to connect two independent clauses)

Sentence 4 is an attempt at a compound-complex sentence (two independent sentences as well as a dependent clause), but it fails because it contains a comma splice. (which is not the correct way to connect two independent clauses)

B) I would suggest the red, white, and blue shoes; they are perfect for the Fourth of July celebration.