Step 1: Understanding the Question
This is a biology question asking to identify the vitamin whose deficiency leads to the disease Beriberi.
(Note: Option C has a typo "Vitamil" which should be "Vitamin").
Step 2: Recalling Vitamin Deficiency Diseases
(A) Vitamin C deficiency: Causes Scurvy.
(B) Vitamin B1 (Thiamine) deficiency: Causes Beriberi, a disease that affects the nervous system and cardiovascular system.
(C) Vitamin B12 deficiency: Can cause a type of anemia (megaloblastic anemia) and neurological problems.
(D) Vitamin D deficiency: Causes Rickets in children (softening of bones) and Osteomalacia in adults.
Step 3: Final Answer
The deficiency of Vitamin B1, also known as Thiamine, causes the disease Beriberi. Therefore, option (B) is the correct answer.