Separate the two benefits:
Ordinary Sickness Benefit: paid for a maximum of 91 days in a year for ordinary illness.
Extended Sickness Benefit: an add-on for specified long-term diseases such as tuberculosis, leprosy and certain cancers, available to those with continuous qualifying employment.
Duration of the extended benefit: It runs for a maximum of 2 years for these chronic conditions, well beyond the basic 91 days.
So: For tuberculosis the extended benefit ceiling is 2 years. The 91-day option is the ordinary benefit trap, and 1 year and 4 years are distractors. Answer: 2 years. Ref: Park PSM, 24e, p.854.