Which of the Following is Not an Inducer of the Lac

Question

Which of the following is not an inducer of the lac operon?
A)allo-lactose
B)IPTG
C)glucose
D)lactose

Accepted Answer

Glucose is a repressor of the lac operon, and when present it inhibits the expression of the operon. The other options are all inducers: lactose is the natural inducer, allo-lactose is an isomer of lactose that is produced as a result of lactose breakdown, and IPTG is a synthetic inducer often used in laboratory experiments as a substitute for lactose.