Stirling Engine

The above left is an ideal alpha type Stirling engine and the above right is a pressure/volume graph of the idealized Stirling cycle. A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work. Which of the following explanations is NOT correct?

a) The pressure of the gas at B is $2P.$

b) The temperature of the gas decreases in the process B $\to$ C .

c) In the process C $\to$ D , the released heat by the gas is the same as the work done on the gas.

d) The gas absorbs heat in the process A $\to$ B $\to$ C .