Final answer:
The disease called 'beriberi' is caused by a deficiency of vitamin B₁ (thiamine) and translates to "I can't, I can't" in Sinhala, referring to the significant weakness and fatigue experienced by those suffering from it.
Step-by-step explanation:
The disease caused by a deficiency of one B vitamin, known to mean "I can't, I can't", is beriberi. Beriberi results from a deficiency of thiamine, also known as vitamin B₁. This condition is characterized by weakness, muscular atrophy, polyneuritis, edema, and cardiovascular changes. There are two main types of beriberi: Dry beriberi, where nervous system symptoms predominate, and Wet beriberi, which is associated with edema and serous effusions. The name 'beriberi' is derived from a Sinhala phrase meaning "I cannot, I cannot," describing the weakness and lethargy associated with the disease.