The correct option is
C Are rich in RuBisCO
A) Bundle sheath cells are rich in RuBisCO.
B) Mesophyll cells lack RuBisCO and Bundle sheath cells are rich in RuBisCO and lack PEP carboxylase.
C) Bundle sheath cells are rich in RuBisCO and lack PEP carboxylase.
D) Mesophyll cells are rich in PEP carboxylase.
So the correct answer is 'Are rich in RuBisCO'.