Assume that max2 is a function that expects two integer parameters and returns the value of the larger one. Also assume that four variables, population1, population2, population3, and population4 have already been defined and associated with integer values. Write an expression (not a statement!) whose value is the largest of population1, population2, population3, and population4 by calling max2.

The expression of the given question is given below

max2(max2(population1, population2), max2(population3, population4))          // it find the largest of  variable by calling method max2.

Explanation:

Following are the description of Expression.

In this population1, population2,population3 and population4 are the variable of integer type that is already mention in the question .We have to find the largest of population1, population2, population3, and population4  variable by calling method  max2.To calling any method we have follow the following syntax

         function_name(parameter list );

So find the largest by passing only two argument we have to firstly calling the outer max2 function that is holding the two inner max2 function. The first max2(population1, population2) is only returning  the one value that is largest another max2(population3, population4)  is returning the one value that is largest.This will merge to the outer function and it returns the largest number.