Tea contains alkaloids called ___ which is a caffeinaceus alkaloid relieving body fatigue.

Correct option is D

Thein is the alkaloid found in tea that is structurally similar to caffeine and is responsible for the stimulating effects of tea.
· It helps in relieving fatigue and promoting alertness.
Explanation:
· (a) Tannin – Tannins are polyphenolic compounds in tea that contribute to its astringency and color, but they do not have the same stimulating effects as thein.
· (b) Trigonelline – Trigonelline is an alkaloid found in coffee and some other plants, but it is not the primary alkaloid in tea.
· (c) Xanthone – Xanthone is a class of compounds found in some plants, including tea, but it is not the primary alkaloid responsible for fatigue relief.
· (d) Thein – Correct answer. Thein is the caffeine-like alkaloid in tea that provides the stimulant effects of relieving fatigue.