Which of the following complete step 4 of the proof?
B
open paren cosine cap A close paren squared times open paren sine cap A close paren squared and cosine squared of open paren cap A minus cap b close paren times sine squared of open paren cap A minus cap b close parenC
open paren cosine squared cap A plus sine squared cap A close paren times open paren cosine squared cap b plus sine squared cap b close paren and cosine squared of open paren cap A minus cap b close paren times sine squared of open paren cap A minus cap b close paren