The correct answer is option 4 - Santhals. On the map of India, the shaded districts represent areas where a specific tribal group constitutes more than 50% of the tribal population. In this case, the shaded districts are indicative of the dominance of the Santhal tribe in these regions.

Although the map is not provided, we can infer from the question that the geographical distribution of the Santhal tribe is highlighted by the shaded areas.

It is important to note that the other three options (Gonds, Bhils, and Nagas) are not the correct answer. The Gonds, Bhils, and Nagas may be significant tribal groups in India, but they are not the particular tribal group referred to in this question.

In summary, the shaded districts on the map represent areas where the Santhal tribe constitutes more than 50% of the tribal population, making option 4 the correct answer.