Answer is C.
Explaination:
L1 is Context Free Language as We can construct a PDA for it easily. Push 'a' then pop 'a' for every 'b' and no need to consider 'c'.
L2 is also Context Free Language. Dont consider 'a'. Push 'b' and pop 'b' for every 'c'.
L3 is also context Free as CFL is closed under Union, Concatenation And Kleene Closure.
As L2 and L3 are CFL. L1 will be CFL.