The correct option is B 15
First pattern = 3 dots
Second pattern = (3 + 3) = 6 dots
Third pattern = (6 + 4) = 10 dots
Starting from 3, every pattern gets added to the next consecutive number (3, 4, 5, 6, 7………..)
Hence, the number of dots in the fourth pattern
= 10 + 5
= 15