Answer:
El statement that say Direct observation is the simplest and most effective method to determine population size is false.
Explanation:
Simple observation results in an inadequate method for estimating the size of a population, especially if it is very large and mobile. A simple and adequate method consists of counting individuals within a population, with some limitations.
Currently, in large populations, it is common to divide an area occupied by a population into quadrants, count individuals, and then extrapolate the data to the actual dimensions of the space occupied by that population.