Why economics often described as the science of constrained choice?

Question

Why economics often described as the science of constrained choice?

Answer 1

resources are limited......like money or time.....and within that scarce set of resources consumer needs to take the optimal decision.........moreover economic models are hypothetical by nature and depending upon a good number of conditions to be fulfilled!!

Answer 2

wants are many,resources are few,choice is inevitable.the choices are constrained because one should choose the best permutation for max benefits