Correct Answer - B
`f_(1)=+40cm` (for convex lens)
`=0.4m`
`f_(2)=-25` (for concave lens)
`=-0.25m`
Therefore, focal length `(f)` of the combination,
`(1)/(f)=(1)/(f_(1))+(1)/(f_(2))`
`=(1)/(0.40)-(1)/(0.25)=(0.25-0.4)/(0.40xx0.25)`
`=-(0.15)/(01)=-1.5D`
`rArrP=(1)/(f)=-1.5D`
(b) is the correct option.
![image](https://learnqa.s3.ap-south-1.amazonaws.com/images/161040765311776362401610407653.png)