What is the grammatical name and function for “which has been in force since 1975”?

Read the excerpts from the land. [willie] turned to my daddy. "it's my boy mitchell done this, mister edward, and i know there ain't no way t' make it up t' ya if this here horse don't heal right, but i jus' 'bout t' put a strap t' mitchell my own self 'bout what he done. i'm gonna put a strap t' him right now, matter of fact! " with that said, he positioned his whip and turned toward mitchell. *** my daddy stopped and looked at me. "no," he said. "i'm not going to whip you, paul. no, your punishment is that you'll never get to ride ghost wind again. i figure you'll remember that a whole lot longer than a whipping. you won't ride any of the other horses either, including the appaloosa, until i say so." which statement about willie’s and mister edward’s reactions is true? both men believe that their sons should be held accountable for their behavior. both men believe that their sons need to learn to handle horses properly. both men believe that their sons will likely harm the horses if they ride them. both men believe that their sons have permanently injured ghost wind

Which is it? the desert is than the mountains? 1. drier 2. more dry

Why was kennedy concerned about the use of nuclear weapons