The most appropriate statement that is explaining the effect and cause during muscle contraction is. “The release of calcium ions causes myosin and actin to attach to each other.” The activation of muscles helps in the generation of muscles that send out the signals to the neurons.
Neurotransmitters is the word you're looking for.
Answer:
Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the limitations imposed by practicality, regulation, safety and cost.
Or,
the person who design and builds or maintain machines or structure..
The crust is not magnetic near the ocean ridges