AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Option A is correct. Both A and R are true, and R is the correct explanation of A. Iodised salt is recommended because iodine is needed for thyroxin synthesis; its deficiency leads to goitre.
The Assertion is a well-known dietary recommendation, and the Reason correctly states the biological purpose of iodine (thyroxin synthesis by the thyroid gland) and the consequence of its deficiency (goitre). Since R directly and completely explains why A is true, option A is the right choice. Note: This topic is from Life Processes (Biology), not the Chemistry chapters provided — but the logic of A-R questions requires checking whether R is the correct explanation of A, which it clearly is here.