Because of the large number of variables under study, an engineer is considering a fractional factorial instead of a full factorial to analyze a process. Apart from the possibility of studying a large number of factors with relatively few experiments, what other characteristic will support a decision to use a fractional factorial instead?

a) it is suspected that there are many interaction .
b) the process is well known and only main factor are of concern
c) a fractional factorial will determine the main effect curvature
d) blocking is necessary to account for nuisance factors in the study