Thioglycolate medium contains the following: yeast extract, pancreatic digest of casein, glucose, L- cysteine, sodium chloride, sodium thioglycolate, and agar. It is considered a complex medium because _______.

A) thioglycolate has a carbon-sulfur bond that many microbes cannot break enzymatically
B) it has multiple ingredients for a broad range of nutrients
C) both yeast extract and pancreatic digest of casein are not chemically de?ned
D) depending on their oxygen utilization pattern, organisms will grow differently on it