The process that is observed both in ${\mathrm{C}}_3$and ${\mathrm{C}}_4$ plants is/are

(a) Photorespiration
(b) Calvin cycle
(c ) Glycolysis

${\mathrm{C}}_3$and ${\mathrm{C}}_4$ plants show both Calvin cycle and glycolysis. In the ${\mathrm{C}}_4$ plants the Calvin cycle takes place in the bundle sheath. Glycolysis takes place in all living organism undergoing aerobic or anaerobic respiration.