Correct Option: A

Photorespiratory loss of CO₂ occurs when RUBISCO starts functioning as an oxygenase instead of carboxylase under conditions of high O₂ and low CO₂. It involves three organelles chloroplast, mitochondria and peroxisomes. Half of the photosynthetically fixed carbon (in the form of RUBP) may be lost into the atmosphere through this process and no ATP formation occurs.