Correct Option: B  [ vitamin B1 ]
Remark:
Explanation: Thiamine (Vitamin B₁) is a water-soluble vitamin essential for carbohydrate metabolism and proper functioning of the nervous system. Its deficiency causes beriberi, which manifests as muscle weakness, loss of appetite, fatigue, and nerve degeneration. There are two main types of beriberi: dry beriberi (affecting nerves) and wet beriberi (affecting the heart).
Rich Sources: Whole grains, legumes, nuts, meat, eggs, and yeast.