To match the boreholes B1, B2, B3, and B4 with their respective features, we need to analyze the schematic diagram provided and understand each feature explained in Group II.

Let's evaluate each borehole:

1. Borehole B1: It penetrates both the piezometric surface and the water table, indicating that it is an artesian well where the water flows out naturally due to pressure. This matches feature 3: artesian well with water flowing to surface.
2. Borehole B2: It is not reaching the water table, suggesting it does not intersect an aquifer. Hence, it should correspond to feature 4: dry well.
3. Borehole B3: This borehole reaches the water table but is below the piezometric surface, implying it is a well in an unconfined aquifer. This matches feature 1.
4. Borehole B4: It intersects the aquifer below the piezometric surface, but the pressure is not enough to bring the water to the surface. So, it is an artesian well with water not flowing to the surface, matching feature 2.

Therefore, the correct match is:

Thus, the correct answer is: P-3; Q-4; R-1; S-2.