Transformation ratio of transformer is ________.

• A. K = V2 /V1 = E1 /E2 = N2 /N1
• B. K = V2/V1 = E2/E1 = N2/N1
• C. K = V1 /V2 = E1 /E2 = N1 /N2
• D. K = V1 /E1 = N1 /E2 = V2 /N2