After 24 Hours Incubation at 35°C in CO₂, the Cystine

After 24 hours incubation at 35°C in CO₂, the cystine trypticase agar tubes of an oxidase-positive, gram-negative diplococcus provides the following reactions:
Control tube-yellow
Glucose-yellow
Maltose-yellow
Lactose-yellow
Maltose-yellow
These results

A) indicate a potential pathogen.
B) indicate a nonpathogen.
C) are invalid.
D) should be read again after an additional 24 hours incubation.