The correct answer is (D) To grow; To increase in extent, quantity, brilliance, intensity, power, etc. To grow or increase in size and brilliance until full.

Wax comes from Old English weaxan (to diminish in amount, intensity, etc. of moon between new and full).

Examples of use:

• Discontent waxed steadily through the period.
• She waxed enthusiastic as they planned the event.