(A) Wes Craven, who was a horror-film director, created a well-known catalog of films
both anchored"Both anchored" and you will read the rest of the sentence hoping you will find "and modifier" but I was disappointed
"Both X and Y" idiom is used incorrectly
(B) Wes Craven, a horror-film director, created a well-known catalog of films anchored
both again "Both" and again wrong. We cant find anything parallel which correctly completes "Both X and Y" idiom
(C) Horror-film director Wes Craven created a well-known catalog of films that was anchoredWe get rid of "Both", thats a good sign

"that" refers to "catalog" correct
We have passive voice "that was anchored" but it's clear and nice (for me)
(D) Horror-film director Wes Craven, who created a well-known catalog of films anchored
the first IC is not an IC at all now, where is the main verb? "who created ...." is just a modifier and then another IC connected with fanboy "yet" begins
(E) Horror-film director Wes Craven, who created a well-known catalog of films anchored both
repeats the error of D and adds "Both" as a bonus
IMO
Ans:
C