Which statement about CMOS detectors is true?

• A. They use only N-type transistors
• B. They use only P-type transistors
• C. They use both N-type and P-type transistors to form the gate
• D. They use neither

Answer: (C)

CMOS detectors rely on both n-type and p-type transistors in a complementary arrangement. In a CMOS gate, a pair of MOSFETs—one n-channel and one p-channel—work together so that when one is on, the other is off. This setup provides low static power consumption and strong, full-range output drive, which are defining benefits of CMOS technology. Using only one type would not realize these advantages and would lead to higher power or poorer performance, while using neither contradicts the fundamental CMOS design. So, using both N-type and P-type transistors to form the gate is the correct description.