Select the odd group of numbers. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g.13 - Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

(15-220-215)

The logic followed here is

Ist number - (Ist number)^{2 -} ( Ist number² - 5 )

(15-220-215) = 15 - (15² -5) -  (15² -10) ODD

(10-100-95) = 10 - (10)² - (10² -5)

(20-400-395) = 20 - (20)² - (20² -5)

(25-625-620) = 25 - (25)² - (25² -5)