The correct answer is option 4, that is, muscle cells require more energy, so they have more mitochondria in comparison to the skin cells.
Mitochondria are the powerhouse of the cells. The synthesis of ATP takes place in them, that is, the energy currencies of the cell. The cells of the muscles need to work hard and thus require ample energy, for this, they need more concentration of mitochondria to generate a high energy yielding ATPs.