Explanation: In DC circuits, power (P) is fundamentally defined as the product of voltage (E) and current (I): P = EI. However, the question specifies that voltage (E) and resistance (R) are known, not current (I). To find the power using E and R, we use Ohm's Law, which states E = IR. From Ohm's Law, we can express current as I = E/R. Substituting this expression for I into the fundamental power formula (P = EI): P = E * (E/R) P = E²/R Therefore, P = (E squared) R is the correct formula when voltage and resistance are known. Option B (P = EI) and C (P = I²R) are also valid power formulas, but they require knowing the current (I), which is not given in the problem statement. Option D is not a standard formula for DC power calculation.