A listless 12 month old boy with a fever of 103oF was taken to the emergency room. He had been diagnosed with an ear infection 3 days earlier. A spinal tap was performed, but only one tube of CSF was obtained from the lumbar puncture. The single tube of CSF should be submitted first to this department.

a. cytology/histology
b. chemistry
c. hematology
d. microbiology