A hospital corridor, which is required to be of fire-resistive construction per the California Building Code, is proposed to have transfer air grilles to assist with ventilation of adjacent rooms. According to Section 407.4.1.3 and its exceptions, under which of the following scenarios would this use of the corridor be permitted?

• For any patient room to improve air circulation.
• When the transfer is caused by pressure differentials in rooms required to have a specific air balance per Table 4-A.
• For a large conference room to provide additional exhaust.
• For a janitor closet of 25 square feet that opens directly onto the corridor.