Primary changes in Acid Base disorders are :
A. Metabolic acidosis decreased plasma bicarbonate
B. Metabolic alkaloses decreased plasma bicarbonate
C. Respiratory alkalosis decreased $pco_{2}$
D. Respiratory acidosis decreased $pco_{2}$
Choose the correct answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : A covlent single bonds in biological molecules have energies similar to the energy of the C-C bond in ethane.
Reason (R) : It is because less electrons are shared between atoms in double bonds they require more energy to break than single bonds.
In the light of the above statements, choose the most appropriate answer from the options given below :