Step 1: The question asks for the CD4 value below which therapy is non-negotiable regardless of how the patient feels. This is an immunological trigger, not a clinical one.
Step 2: Within the older NACO staging logic, the 200 to 350 window is a zone of clinical judgement: symptomatic patients are treated, asymptomatic ones are watched and may have the CD4 repeated to exclude lab error of about 20 percent.
Step 3: Once the count slides under 200, the immune system is sufficiently compromised that ART is mandated whether or not opportunistic features are present. That fixed floor is the value the stem wants.
Step 4: Hence 100 and 150 sit below the decision point and 350 marks the soft upper margin, leaving 200 as the symptom-independent threshold.
\[\boxed{200\ \text{cells/mm}^3}\]