Question

What is regeneration ?state a reason why are more Complex organisms cannot give rise to a new individual through this method

Answer 1

regeneration is the process in which new organism are reproduced by the cut out parts of parent organism. This happens with the help of special tissues.
Complex organism cannot give rise to a new individual through this method as complex organisms have different cells . These cells make up different tissues and then different organs. Every organ has its own structure and way of functioning. These organs just cannot be cut to give rise to new organisms

hope this would help u and if it does plzz mark it as brainlist :):)

Answer 2

The question itself is an answer "complex".

Large and complex organisms have different organs and organs systems which perform different functions in a body. Millions of cells join together to make these structures however these cells do not have an ability to regenerate  into a new organisms. I mean a single or a group of cells can't develop into different types of organs with different functions.