Correct Answer - B
Efficiency of cycle `=("Area of closed cycle")/("Area under the curve")xx100`
`=((1)/(2)xx(1500-1000)xx(250-150))/((1)/(2)xx(1500-1000)xx(250xx150)+(1500-1000)xx(150-0))xx100`
`=((1)/(2)xx500xx100)/((1)/(2)xx500xx100+500xx150)xx100`
`=(500xx50xx100)/(500xx50+500xx150)=25`.