What is the main disadvantage of the counter-ramp A/D converter?

• A. It requires a counter.
• B. The counter must count up from zero at the beginning of each conversion sequence, and the conversion time will vary depending on the input voltage.
• C. It requires a precision clock in order for the conversion to be reliable.
• D. The counter must count up from zero at the beginning of each conversion sequence, and the conversion time will vary depending on the input voltage. It requires a precision clock in order for the conversion to be reliable.