Answer:
BCIP/NBT
Explanation:
BCIP/NBT is a colorogenic substrate used for AP. AP stands for alkaline phosphatase. When they are catalyzed with this alkaline, we would have a product that has a dark blue or probably a purple color. NBT stands for nitro blue tetrazolium. Both of these work as substrate for the reaction. BCIP oxidizes BCIP to form this color.