D

Step 1: Understand what a magnetic dipole moment is. The magnetic dipole moment () of a current loop is defined as the product of the current () flowing through the loop and the area () of the loop:
'M = I imes A'
Step 2: Analyze the direction of the magnetic dipole moment. For a rectangular loop, the magnetic dipole moment is always perpendicular to the plane of the loop, following the right-hand rule.
Step 3: Consider the proportionality. The magnetic dipole moment is directly proportional to the current and the area of the loop.
Step 4: Conclude: Thus, the magnetic dipole moment is perpendicular to the plane of the loop and proportional to the area of the loop. Hence, the correct option is D.