Cоnsider а triаngle mаde оf circles arranged in rоws, such that the nth row in the triangle contains n circles as shown in the figure below. For example in T3 = 6, the first row has 1, second row has 2, and the third row has 3 circles, with the total number of circles to be 6. Write a recursive function int triangle(int n) that returns the total number of circles in a triangle containing n rows. You must use recursion. Iterative solution will receive 0 marks for this problem.