In contrast, patients receiving a single course of teplizumab demonstrated a relative increase in C-peptide levels, suggesting not only a delay in beta cell destruction, but also the recovery of sick or dying beta cells and the restoration of their functionality and insulin secretion.
Take context from the input text and decide on the accurate relationship between 'beta cell' and 'insulin' from the options provided.
Options: owner of, operator, headquarters location, product/material produced