What is the value of Young's modulus for a perfectly elastic body?

MY PREVIOUS SOLUTION IS INCORRECT.

for a perfect elastic body the stress strain graph is always linear, meaning stress is always proportional to the strain through a constant i.e., the youngs modulus of elasticity which is proportional to the slope of the linear property of the stress strain graph. if a body is ideally plastic it means to have infinite linear line from the centre of the stress strain graph. A linear line like this could have any slope=tan θ.this linear line could have any angle meaning any slope can values between 1 and 0 implying that youngs modulus could be any value.

i think that for a perfectly elastic body stress directly proportional to strain 1