CONCEPTS: The basics of Profit/Loss have been applied in the question.

SOLUTION:

A=20$kg, B=24$kg ,C =30$kg
Let x kg be rice A ,y kg be rice B and 2 kg be quantities of rice C
Final CP = 25

Equating the Cost Prices we have-
20x+24y+60=25(x+y+2)
=>y=10−5x
Since, y cannot be zero or negative and for any value of x above 1 we have 0 or negative y
x can only be 1 giving y=5 kg (OPTION C)