Consider L as any CFL [say wwr] and choose R = {ϵ} [as R is given Regular in question]
So Now for all x in L, there exist y i.e ϵ such that xy ϵ L [as xy = xϵ = x and x is in L only]. So L/R is nothing but L itself.
Hence L/R is CFL and hence recursive too [so option c is false]
Only correct option is B.