Read the following statements w.r.t. cellular respiration and select the correct option:
(A) The breaking of C-C bonds of complex substances through oxidation occurs in the absence of oxygen.
(B) All the energy present in respiratory substance is not released free into the cell.
(C) Energy is released in a series of slow stepwise reactions in presence of enzymes.
(D) The energy released by breakdown of C-C bonds is not used directly for cell metabolism.

Statement (A) is incorrect. The breaking of C-C bonds of complex substances through oxidation primarily occurs during aerobic cellular respiration, which requires oxygen.
Statement (B) is correct. During cellular respiration, not all the energy present in respiratory substances (such as glucose) is released freely into the cell. Instead, the energy is captured in the form of high-energy molecules such as ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide).
Statement (C) is correct. Energy is released in a series of slow stepwise reactions during cellular respiration, which occur in the presence of enzymes. These enzymatic reactions involve the breakdown of respiratory substrates and the transfer of electrons through the electron transport chain, leading to the production of ATP.
Statement (D) is correct. The energy released by the breakdown of C-C bonds during cellular respiration is not used directly for cell metabolism. This energy is captured in the form of ATP, which is the primary energy currency of the cell and is then utilized for various cellular processes.