Assume we have a PDA that never pops the stack. From the following, select the type of languages this PDA can recognize.

a$.$ Context$-$free languages generated from a right$-$regular grammar

b$.$ Context$-$Free languages

c$.$ Languages defined as an intersection of a context$-$free language with a non regular language

d$.$ Languages defined as an intersection of a context$-$free language with a regular language