The correct answer is 'C. Supercomputers are focused to execute few programs as fast as possible while mainframe uses its power to execute as many programs concurrently' because it highlights the key distinction between the two types of computers. Supercomputers are designed to handle complex calculations and execute a small number of programs quickly, while mainframes are built to handle multiple tasks simultaneously, making them ideal for multitasking and handling a high volume of transactions efficiently. This explanation clearly defines the primary purpose and functionality of each type of computer, emphasizing their respective strengths and focuses.