Consider the context$-$free grammar with the following production rules, and $S$ the start symbol.

Then select one answer that represents the variables for the grammar.

$SCbcCb$

$C$aCb$|ab|$

Select one or more:

$S,C,a,b,c$

$a,b,c$

$S,C,B$

$S,C$

$S,C,a,c,b,$