Step 1: Understanding the Concept:
Vitamins are essential nutrients that the body needs in small amounts. Each vitamin deficiency leads to specific clinical symptoms.
Step 2: Formula Application:
1. Vitamin $B_1$ (Thiamine): Beri-beri.
2. Vitamin $B_2$ (Riboflavin): Cheilosis.
3. Vitamin $C$ (Ascorbic Acid): Scurvy.
4. Vitamin $B_6$ (Pyridoxine): Convulsions.
Step 3: Explanation:
Pyridoxine ($B_6$) is involved in amino acid metabolism and neurotransmitter synthesis. Its deficiency affects the nervous system, leading to irritability and convulsions (seizures).
Step 4: Final Answer:
The deficiency of pyridoxine leads to convulsions.