Final answer:
Terms like 5x and -4x, 7p^2q and 2p^2q have the same variable factors and are known as like terms, which can be combined through addition or subtraction.
Step-by-step explanation:
The terms in question (5x and -4x, 7p^2q and 2p^2q) can be classified according to the options provided. These terms have the same variable factors but different coefficients. The correct term from the options given is e. like terms. Like terms are terms that contain the same variable(s) to the same power. Hence, they can be combined through addition or subtraction due to their like variables.
Moreover, when manipulating equations, it is important to keep in mind that every term on each side of an equation must have the same dimensions to make logical sense. This means that you cannot add or subtract terms with different variables or powers, as they represent different entities or dimensions. When calculating with equations, it's often necessary to consider the variables on the left-hand side one at a time, holding the others constant, to isolate and solve for a specific variable.