What is the approximate earth's dipole moment, if the earth's magnetic field at the Equator is approximately 0.5 G and diameter is $15.0 × 10^6m$?

$1.05 × 10^8 Am^2$ $6.5 × 10^{30} Am^2$ $2.1 × 10^{23} Am^2$ $1.05 × 10^{23} Am^2$

$2.1 × 10^{23} Am^2$

The correct answer is Option (3) → $2.1 × 10^{23} Am^2$