The Vitamin A activity of beta-carotene compared to that of retinol is?: (A) 2-Jan, (B) 4-Jan, (C) 6-Jan, (D) 8-Jan
Answer is C. Beta-Carotene (provitamin A): 

This is found in plant foods. lt is cleaved in the intestine to produce two moles of  retinal.
ln humans, this conversion is inefficient, hence beta-carotene possesses about  one-sixth vitamin A activity compared to that of retinol.

Reference: Satyanarayana- Biochemistry, 3rd edition, pg-119