**Core Concept**
A convergent concomitant squint in a 2-year-old child refers to a type of strabismus characterized by a constant angle of deviation between the two eyes in all directions of gaze. This type of squint is often associated with a lack of binocular vision and can lead to amblyopia if left untreated.

**Why the Correct Answer is Right**
In a convergent concomitant squint, the angle of deviation remains constant regardless of the direction of gaze. This is due to a misalignment of the extraocular muscles, which are responsible for controlling the movement of the eyeballs. The correct answer is related to the underlying pathophysiology of this condition.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a non-paralytic squint typically refers to a type of strabismus that is not associated with a paralysis of the extraocular muscles.

**Option B:** This option is incorrect because a paralytic squint typically refers to a type of strabismus that is associated with a paralysis of the extraocular muscles, which is not consistent with a concomitant squint.

**Option C:** This option is incorrect because a heterotropia squint refers to a type of strabismus where the angle of deviation varies with the direction of gaze, which is not consistent with a concomitant squint.

**Clinical Pearl / High-Yield Fact**
A key aspect of managing a convergent concomitant squint is to address any underlying amblyopia through patching or other forms of vision therapy.

**Correct Answer:** C.