A clinical thermometer is a thermometer used to measure human body temperature. Most made in the 20th century are mercury-in-glass thermometers. They are accurate and sensitive, having a narrow place where the mercury level rises very fast. A kink in the tube stops the mercury level from falling on its own.
These thermometers are used in clinics by doctors, so they are also called a doctor's thermometers or medical thermometers. Most show both Celsius scale and Fahrenheit temperature scales. The scale runs from 35 degree Celsius to 42 degree Celsius. Hence Option A is correct. The rest of the options do not adhere to this rule, hence, incorrect.