The question asks to identify the incorrectly matched pair between a vitamin and its deficiency disease.

Identifying Incorrect Vitamin-Disease Pairs

To find the incorrect match, we need to examine the known deficiency diseases associated with each vitamin listed:

• Vitamin B1 Deficiency: Causes Beriberi.
• Vitamin B3 (Niacin) Deficiency: Causes Pellagra.
• Vitamin B12 Deficiency: Causes pernicious anemia and Subacute combined degeneration of the cord.
• Vitamin B5 (Pantothenic Acid) Deficiency: Can lead to symptoms like Burning feet syndrome.
• Vitamin B6 Deficiency: Associated with neurological issues like convulsions, depression, and peripheral neuropathy, but not primarily Beriberi.

Analyzing Option Pairs

Let's evaluate each option based on established medical knowledge:

• Option 1: Vitamin B6 - Beriberi. Beriberi is caused by Vitamin B1 (Thiamine) deficiency. Vitamin B6 deficiency has different symptoms. Therefore, this pair is incorrectly matched.
• Option 2: Vitamin B3 - Pellagra. Pellagra is the classic deficiency disease of Vitamin B3 (Niacin). This match is correct.
• Option 3: Vitamin B12 - Subacute combined degeneration of cord. This neurological condition is a known consequence of Vitamin B12 deficiency. This match is correct.
• Option 4: Vitamin B5 - Burning feet syndrome. Burning feet syndrome is often associated with the deficiency of Vitamin B5 (Pantothenic Acid). This match is correct.

Based on the analysis, the pair that is not correctly matched is Vitamin B6 with Beriberi.