The question asks about a low-pressure belt near the equator and provides four options. The correct answer is "Doldrums." Let's explore why this is the correct choice by examining each option:

1. Polar Front: This refers to the boundary at high altitudes where the cold polar air meets the warmer air from the mid-latitudes. It is not related to the equator, so this is incorrect.
2. Horse Latitudes: These are subtropical regions known for calm winds and little precipitation, located around 30 degrees north and south of the equator. This region is characterized by high pressure, not low pressure, so this is incorrect.
3. Doldrums: This is an area near the equator, known scientifically as the Intertropical Convergence Zone (ITCZ), characterized by low pressure and calm winds. Sailors used to get stuck in this windless area, which is why it was called the "Doldrums." This is the correct answer.
4. Trade Wind Belt: These are prevailing winds found around the equatorial region, blowing from the northeast in the northern hemisphere and from the southeast in the southern hemisphere. While related to the equator, the Trade Wind Belt is distinct from the low-pressure area known as the Doldrums.

Thus, the Doldrums is the correct term for the low-pressure belt near the equator, characterized by calm winds and significant rainfall. This conceptual understanding is essential for geography-related sections in many competitive exams.

Conclusion: The correct answer is Doldrums, as it specifically denotes the low-pressure area near the equator.