There is no Coriolis force at the equator because

air moves only in a straight line near the equator.

there is only translational movement at the equator, not rotational motion.

there are few storms at the equator.

all of the above.

There is no Coriolis force at the equator because there is only translational movement at the equator, not rotational motion.

Explanation:

The Coriolis effect, described in 1836 by the French scientist Gaspard-Gustave Coriolis, is the effect observed in a rotating reference system when a body is in motion with respect to said reference system. This effect consists in the existence of a relative acceleration of the body in said rotating system. This acceleration is always perpendicular to the axis of rotation of the system and the speed of the body.

The Coriolis effect causes an object that moves over the radius of a rotating disk to accelerate with respect to that disk depending on whether the movement is towards the axis of rotation or away from it. By the same principle, in the case of a rotating sphere, the movement of an object on the meridians also has this effect, since said movement reduces or increases the distance from the sphere of rotation of the sphere.

The most notorious example of the manifestation of the Coriolis effect is when air or water masses move along terrestrial meridians, and their trajectory and velocity are modified by it. In fact, the oceanic winds or currents that move following a meridian deviate accelerating in the direction of rotation (east) if they go to the poles or vice versa (west) if they go to the Equator. It can be added that, consequently, in the Equator, there is no Coriolis effect.