Match Each Molecule with Its Description

Match each molecule with its description.
-troponin

A) molecules that form a twisted double helix that makes up most of the thin filaments
B) neurotransmitters involved in muscle cell contraction
C) molecules that block the crossbridge binding sites when the muscle is not contracting
D) molecules that make up thick filaments
E) molecules that bind to Ca²⁺, change their shape, and then uncover the crossbridge binding sites