Review the item:
Derek wanted a ferocious pit bull terrier to scare off
burglars,
but his apartment complex did not allow dogs as a result, Derek had
to settle for naming his goldfish Mr. Jaws and installing additional door
locks.
Derek wanted a ferocious pit bull terrier to scare off burglars is a main clause. His apartment complex did not allow dogs is also a main clause. A comma and a coordinating conjunction like but can legally connect two main clauses.