[单选题]
A gas is confined to a rigid container that,sprtuz bdvlkx ) y3.qk jp;5e5j4 *)o can0+ fs tsj tz/ecug(s 4;gsxw--(d4 fisnot expand as heat energy is added to it. Thiswsgi0ufst+gj4c t ; de-zf (4-xss/s ( process is
A. isothermal
B. isochoric
C. isobaric
D. adiabatic
