B)Vitamin B

Explanation:
Thiamine, also known as vitamin B1, is a water-soluble vitamin. It is one of the eight B vitamins, which play essential roles in maintaining good health. Thiamine is the first vitamin in the B complex vitamin group, hence its classification as vitamin B1.

Thiamine plays a crucial role in the body's energy metabolism. It helps convert carbohydrates into glucose, which is the body's primary source of energy. This process is important for the proper functioning of the brain, heart, muscles, and nervous system.

Thiamine is also involved in the synthesis of neurotransmitters, such as acetylcholine, which are essential for proper brain function and nerve transmission. It is also necessary for the production of DNA and RNA, the genetic material of the body.

Sources of Thiamine:
Thiamine can be obtained from a variety of food sources, including:
- Whole grains (such as brown rice, oatmeal, and whole wheat)
- Legumes (such as beans, lentils, and peas)
- Nuts and seeds (such as sunflower seeds and flaxseeds)
- Pork
- Fish (such as trout and tuna)
- Organ meats (such as liver and kidney)

Deficiency and Symptoms:
A deficiency of thiamine can lead to a condition known as beriberi. Symptoms of thiamine deficiency may include:
- Fatigue and weakness
- Loss of appetite
- Weight loss
- Confusion and memory problems
- Muscle weakness and pain
- Tingling or numbness in the hands and feet

It is important to consume an adequate amount of thiamine through a balanced diet to prevent deficiency. Most people can meet their thiamine needs through a varied and nutritious diet. However, in some cases, such as alcoholism or certain medical conditions, thiamine supplementation may be necessary.

In conclusion, thiamine is a type of vitamin B, specifically vitamin B1. It is essential for energy metabolism, brain function, and nerve transmission. Good food sources of thiamine include whole grains, legumes, nuts, seeds, pork, fish, and organ meats.