An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and If is the final temperature, which of the following statements is correct ?
(A) Tf > Ti for reversible process but Tf = Ti for irreversible process
(B) (Tf)rev = (Tf) irrev
(c) Tf = Ti for both reversible and irreversible processes
(D) (Tf) irrev > (Tf) rev