A cell is capable of accomplishing a wide array of tasks all of itself. Multiple processes, such as cellular respiration, transport, protein formation etc. takes place inside the cell. Such different functions necessary for the survival of an organism can be performed by the cell because of the specialized functions of the organelles. The cell organelles perform their functions to help the cell to survive. The phagocytes carry out phagocytosis, the mitochondria generates ATP, the ribosomes help in protein formation. These specialized functions are what helps a cell to perform so many function alone.
Hence, the correct answer is 'Option D - The organelles have specialized functions.'