Postdoctoral Research Fellow Camilla Performs a Radioligand Binding Assay

Postdoctoral research fellow Camilla performs a radioligand binding assay. After assessing radioactivity with a scintillation counter, she finds that her radioactive counts are very low. What does this mean?

A) The radioligand bound to many receptors, preventing it from passing through the filter.
B) The radioligand bound to many receptors, allowing it to be retrieved from the filter.
C) The radioligand bound to few receptors, preventing it being retrieved from the filter.
D) The radioligand bound to few receptors, allowing it to pass through the filter.