What Are Chaperonins ("Molecular Chaperones")

What are chaperonins ("molecular chaperones") ?

A) Channels in the membrane for protein secretion.
B) Proteins used for the secretion of other proteins.
C) Proteins used for the correct folding of other proteins.
D) Proteins involved in the regulation of gene expression at the level of transcription.
E) Sensory proteins found in the cytoplasmic membrane to sense various environmental signals.