Of the Four Steps in the Carnot Cycle

Of the four steps in the Carnot cycle,

A) two are isothermal and two are isobaric.
B) two are adiabatic and two are isobaric.
C) two are isovolumic and two are isothermal.
D) two are adiabatic and two are isothermal.
E) two are adiabatic and two are isovolumic.