What is a protein that is the main component of the thick filaments in muscle fibers and is responsible for muscle contraction?

The answer is myosin. Myosin are contractile protein the makes up thick filament. The molecule consists of a tail and two myosin heads which bind to myosin binding sites on actin molecules of thin filaments during muscle contraction. Actin on the other hand are contractile proteins that are the main component of thin filament. Each actin molecule has a myosin-binding site where myosin head of thick filament binds during muscle contraction. 

This is what i found on google“ the monomers combine with each other via covalent bonds to form larger molecules known as polymers. in doing so, monomers release water molecules as byproducts. this type of reaction is known as dehydration synthesis, which means “to put together while losing water. in the process, a water molecule is formed.” i hope this you

Yes they are correct good day