Question

which type of sentence is this? since 1923, the united states flag code has provided advisory rules for displaying and handling the u.s. flag. simple compound complex compound - complex

Explanation:

A complex sentence has one independent clause and at least one dependent clause. The given sentence has an independent clause "the United States Flag Code has provided advisory rules for displaying and handling the U.S. flag" and a dependent adverbial clause "Since 1923" (a dependent clause cannot stand alone as a complete sentence).

Answer:

complex