Why Is an Evaluation That Uses Only Synthetic Programs Inadequate

Why is an evaluation that uses only synthetic programs inadequate for predicting performance?

A) In general, it is a good idea to use more than one evaluation technique to confirm the results obtained from each type of evaluation.
B) Synthetic programs are not real programs and typically target only a specific subsystem so they do not evaluate how the overall system will perform while executing real programs.
C) Synthetic programs provide valuable insight into which components are creating bottlenecks, but they do not always indicate the precise cause of a component's inefficiency.
D) all of the above