A 16-year-old boy comes to the clinic complaining of fever and malaise for the past 2 days. On examination, his temperature is 37.8 °C with tender cervical lymphadenopathy. Laboratory studies show hemoglobin 12.5 g/dL, platelet count 225,000/cumm and WBC count 12500/cumm. His peripheral blood smear shows frequent atypical lymphocytes.

These atypical cells express which of the following CD markers?