The Advantages of Using the PET Plasmid System Include ____

The advantages of using the pET plasmid system include ____.

A) genes to be expressed are under the control of a T7 promoter
B) the T7 polymerase is slower than a typical E coli polymerase
C) the expressed protein never accounts for more than 5% of the total cell protein
D) the T7 polymerase is under the control of the lac operon and is thus only active when induced by an agent such as IPTG
E) both a and d are correct