Explanation:

- Let’s call the cost of a pear = P, guava = G, and mango = M.

- From the given: 10P + 8G + 6M = 44.

- Each fruit cost is a natural number, all are different.

- Since all are natural numbers, let's try small values so that the sum is 44.

- P, G, M must be all different and minimal; let's test logical values:

- Assume pears are the cheapest. Try P = 1: 10*1 + 8G + 6M = 44 ? 8G + 6M = 34.

Let's try G = 2: 8*2 = 16, 34-16=18, so 6M=18?M=3 (All numbers 1,2,3 and different—possible).

Sum: (10*1) + (8*2) + (6*3) = 10 + 16 + 18 = 44

Therefore, P=1, G=2, M=3.

- Cost for 4 mangoes + 3 guavas: 4M + 3G = 4*3 + 3*2 = 12 + 6 = 18.

Option 2, Rs. 18 is correct.