What is the formula for the area of the magnet in the design of PMDC motors?

• A. area of magnet = flux * 4.95 * residual flux density
• B. area of magnet = flux / 4.95 * residual flux density
• C. area of magnet = flux * 4.95 / residual flux density
• D. area of magnet = 1/flux * 4.95 * residual flux density