Which of the Following Is Not a General Guideline for Balancing

Which of the following is not a general guideline for balancing an equation?

A) Write correct formulas for reactants and products.
B) Begin balancing with the most complex formula.
C) Balance polyatomic ions as a single unit.
D) Check each reactant and product to verify the coefficients.
E) Change a subscript in a formula if the equation is not balanced.