Muscle cells are also called fibers because they are like tissues and move easily
Water means it is the mixture of hydrogen and oxygen. As we know that
hydrogen is colourless as well as oxygen is also colourless gas.
So at last when hydrogen and oxygen reacts with one another and they
form H2O means water. If both are colourless so their product will also
be colourless. So water is seen colourless.
I believe that the answer to your question would be A. Heart Begins.