Step 1: Recall the deficiency table:
A quick way to solve this is to link each nutrient with its disease. Iodine goes with goitre and cretinism. Iron goes with anemia. Vitamin A goes with night blindness.
Step 2: Sort the four statements:
Goitre matches iodine. Mental retardation matches iodine (through cretinism in infants). Anemia matches iron. Night blindness matches vitamin A.
Step 3: Pick the option:
The set of iodine-related symptoms is {A, B}. Anemia (C) and night blindness (D) belong to other nutrients, so any option containing C or D is wrong. Options 2, 3 and 4 all contain C or D.
Step 4: Conclusion:
Only option 1 contains just A and B, so it is the answer.
Final Answer:
Only goitre and mental retardation relate to iodine, so the answer is option 1.
\[\boxed{1}\]