Which of the following membrane has the highest protein content per gram tissue

The cell membrane contains proteins and lipids in a mass ratio of 50:50. The ratio is not absolute and varies from the membrane to membrane. The exact ratio between the two varies with the function of the cell. For example, the myelin sheath of nerves has ~75% lipids and 25% proteins, whereas membranes involved in energy transduction, such as the inner mitochondrial membrane, have 75% proteins and 25% lipids.Reference: Sircar Principles of Medical Physiology; 1st edition; Page no: 36