Which of these Sentence is incorrect?

Select an alternative you consider both most correct and most effective according to the requirements of standard written English: Most of the children like to read these kind of books for their bedtime reading.

Choose the incorrect part:
Cans of paint must be shaking to mix the pigments with the medium in which in which they are suspended.

Pick out the incorrect sentence

Anthropologist asserts that many of the early Native Americans who lived on the Plains did not engage in planting crops but to hunt, living primarily on buffalo meat. Here which of the underlying word is incorrect?