Why is including a loop of observation during the construction stage of a project an important component of the engineering design process?

a$.$ The knowledge and techniques that are required to realize the design concept are not yet available.

b$.$ Non$-$technical factors influence the design process.

c$.$ Not all the conditions of the project site or the absolute accuracy of all assumptions can be established prior to construction.

d$.$ The functional criteria for the solution to the problem are important.