In Interstellar Professor Brand reveals only to Murph (on his deathbed) that Plan A, solving the equation was 'impossible'. I am struggling to reconcile;
A) How Murph knows that it is quantum data needed to solve the equation.
B) How Cooper knows that in order to save humanity, he must send the quantum data to Murph i.e. that the solution to the equation requires quantum data.
I get that with A) Murph could join the dots and realise what to do with this data but it is B) I am more struggling with. Was this just a last Hail Mary or had he figured out himself the quantum data would solve the equation, did he have a scientific background?
In no way is this a criticism of the movie, I would just like to understand it more.