In an isochoric (等容) process, all the energy added as heat remains in the system as an increase in internal energy.

For a system of an ideal gas, in which process of the following that the heat absorbed by the system and the work done toward the surroundings are positive? A: Isochoric (等体) and pressure decreasing process. B: Isothermal (等温) and expanding process. C: Adiabatic and expanding process. D: Isobaric (等压) and compressed process