need help on a trophy the a plausible explanation trophy

[dangerousbrian0]

hi there i am stuck on getting the a plausible explanation trophy i am not sure what you have to do to get the trophy the description under the trophy says discovered the origins of the new delorean

[Martin McFly]

Talk to Doc while he's in the prison before you talk to his younger self. One of the conversation options is about the DeLorean. Talk to him about it.

[dangerousbrian0]

ok thanks i shall do that