Indicate which period of the Mesozoic era are subdivided into three divisions.

This era includes three periods: Cretaceous, Jurassic and Triassic. The Jurassic and Triassic periods are divided into three divisions. So the Triassic period consists of an upper, middle and lower section, which in total occupy a time interval of 251.5 million – 201.5 million years ago. At the same time, the Jurassic is also divided into upper, middle and lower sections, which spanned the time period from 201.5 million to 145 million years ago.