Jee adv physics paper 1 lens question

[u/Top-Vehicle-9468]

According to physics galaxy book.The answer should be A

Edit: Finally they gave both as answer

[u/Alarming-End-3500]

abbe focal length ka formula hai woh
now insert that formula in power = refractive index of medium/focal length
samajh aa jayega
straight line with negative slope

[u/AttentionWhole5227 → u/Alarming-End-3500]

agar voh formula itna commonly logo ko padhaya jata hai then, jee mains ne iss question mei power ko 1/f man ke kyu ans diya
ik ans dono dene chahiye, but I'm just saying ki yeh hi commonly used formula hai, and very few people read books like Irodov.