Which of the following statement are correct?
A. `alpha`-Amino acids on heating give piperazine (cyclic diamide).
B. `beta`-Amino acids on heating give `alpha,beta`-unsaturated acids.
C. `gamma-`Amino acids on heating give lactam (five-membered cyclic ester).
D. `delta`-Amino acids on heating give lactam (six-membered cyclic ester).
