Which book is the first known written study on tea?

Which book is the first known written study on tea?

A Treatise on Tea by Emperor Song Huizong
B The Classic of Tea by Lu Yu
C The Record of Tea by Cai Xiang

The Classic of Tea, also known as Ch’a Ching, was written between 760 CE and 762 CE, during the Tang dynasty. It is the first definitive work on cultivating, making and drinking tea. The original manuscript, which was lost, consisted of three books totaling 10 chapters.

The correct answer is The Classic of Tea by Lu Yu.