Comprehensive and Detailed Explanation:
AIIR for TB: ASHRAE 170, Section 7.2.1, allows supplemental ventilation (e.g., recirculation units) if HEPA- filtered to remove TB bacilli. Exhaust is preferred, but recirculation is permitted with HEPA filtration (CDC guideline).
Option Analysis:
A: Correct-HEPA filtration is mandatory for recirculated air.
B: Incorrect-Return air is exhausted, not recirculated via AHU.
C/D: UVGI and 100% OA are optional, not required.