This checks basic knowledge of global wind belts taught in physical geography.
Near the Equator: correct. The doldrums, also called the equatorial calms, lie near the equator where the northeast and southeast trade winds meet. Intense heating makes air rise vertically instead of blowing steadily, so surface winds are weak and unpredictable.
Near the Poles: the polar regions have polar easterlies, a different wind system, not the doldrums.
Near the Tropic of Cancer: this latitude falls in the belt of trade winds and subtropical high pressure, not the doldrums.
Near the Tropic of Capricorn: same reasoning as the Tropic of Cancer, this is a subtropical high pressure zone, not the equatorial calm belt.
The correct option is A, near the Equator, where converging trade winds create the calm, low pressure doldrums belt.