Night blindness is a condition where a person is unable to see clearly in dim or low light conditions. The correct cause of night blindness is option 3, which is Vitamin A deficiency. Vitamin A is essential for maintaining the health of the retina, which is the part of the eye responsible for vision in low light. When there is a deficiency of Vitamin A, the retina cannot function properly, leading to night blindness.

Option 1, less drinking of water, is unrelated to night blindness as it does not directly affect the functioning of the eyes. Option 2, excess secretion of the pineal gland, is also not related to night blindness as the pineal gland is involved in the regulation of sleep-wake cycles and not vision. Option 4, inheritance by X-chromosome, is incorrect as night blindness is not exclusively inherited through the X-chromosome.

In summary, the correct cause of night blindness is Vitamin A deficiency.