The correct option is D liberation of energy
Cellular respiration is the set of metabolic reactions and processes, that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process. Respiration is one of the key ways a cell gains useful energy to fuel cellular activity. So, a very important feature of respiration is liberation of energy. Thus, option D is correct.
Respiration involves in synthesis of some of complex compounds. But its not the major feature of respiration. Thus, option A is wrong.
Respiration does not involves utilization of CO2 or liberation of O2. Thus, option B and C are wrong.