The puffed-up appearance of dough is due to the production of:

The correct answer is Option (1) → Carbon dioxide gas

Option (1) Carbon dioxide gas — Correct. The microbes in the dough ferment its sugars and release CO₂, which forms small bubbles.

Option (2) Alcohol — Incorrect. Fermentation also gives some alcohol, but alcohol is a liquid and cannot make the dough rise.

Option (3) Acetic acid — Incorrect. Acetic acid is made from alcohol by Acetobacter aceti (vinegar); it plays no part in raising dough.

Option (4) Oxygen gas — Incorrect. Fermentation does not release oxygen; it goes on without oxygen.

Note: A similar question was also asked in CUET (UG) 2026 on 22-05-2026 (Slot 2), and in CUET (UG) 2025 on 23-05-2025 (Slot 2).

NCERT Extract:
Microbes in Household Products – “… The dough, which is used for making foods such as dosa and idli is also fermented by bacteria. The puffed-up appearance of dough is due to the production of CO₂ gas.”