Final answer:
The exact number of dancers featured at the start of "under" at the UofSC Dance Concert is not provided in the information available. To obtain this detail, one would need to reference the event's program or contact the university's dance department.
Step-by-step explanation:
The performance of "under" at the UofSC Dance Concert does not specify the exact number of dancers that were featured at the start of the dance within the provided information. Since the facts available do not include details about this particular performance, it is not possible to provide a definitive answer. For accurate information, one would need to consult the program or reviews of the event, or contact the University of South Carolina's dance department directly.