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A level physics question, need help with clearing concept

https://qrpastpapers.com/exam/2700?question_number=19
Apparently the answer is B because the metal is same so young modulus is the same therefore the stress strain relationship will be the same. But my confusion lies in the shape of the graph since it is a curve and clearly beyond the elastic limit. As far as I understand, the young modulus is defined within the elastic limit(since it is the proportionality constant between stress and strain which are only proportional within the elastic limit) so how does that apply here? And if the young modulus still applies (simply as stress to strain ratio) beyond the elastic limit, then would it not change after the elastic limit since the graph curves? That would mean it would vary from object to object even if of the same material, as far as I understand, since the elastic limit varies. So how does the logic I stated at the beginning work? I am sorry if this is a long read but this has been bothering me for the past hour. Thanks!
(edited 1 year ago)
I think it's more to do with the fact that it's a stress-strain graph. The material is kept constant so the values for strain at a certain stress would still be the same, but I'm not too sure

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