Answer:
The correct answer would be "Myosin heads attach to sites on actin filaments".
The muscle cell or myofibril consists of two types of protein filaments namely; actin (thin filament) and myosin (thick filament).
The myosin heads attach to the binding sites on the actin filaments and pull it towards the M-line in order to produce contraction.
The hydrolysis of ATP provides energy for this contraction cycle.
For the answer to the question above, I think that Few Fossils exist from this time because the animals were all soft-bodied. Most of the animals dissolve or decompose immediately and turn to dust because they are soft-bodied.
