The correct choice is (d) Depends on the number of variables
Explanation: If we have a very big expression relating a variable y with any no. of variables x1,x2…xn we can put the entire expression on the right hand side within a function and reduce the expression to
y=func(x1,x2,x3…xn)
This contains two expressions only. The function, ‘func’, may contain a set of 10000 statements. But we have simplified the expression to demonstrate a mathematical relation between y and all the other variables of the right-hand side, provided we are sure about the nature of the function ‘func’.