Final answer:
The red hand of the duplex air gauge indicates the pressure is in the range of 21-114 psi, which is the typical range for tire pressures and uses a standard unit of pressure measurement.
Step-by-step explanation:
The red hand of the duplex air gauge is typically used to indicate the pressure in the tires. To answer the question correctly, it is important to use the typical units of pressure measurement in this context. Given the options, pressures are commonly measured in psi (pounds per square inch) for tire pressures. Using the provided information, 1 atm is equivalent to 760 mmHg and 101.325 kPa. Therefore, when considering the range of tire pressures that a typical gauge might measure, option 1) 21-114 psi is appropriate as it falls within the expected range for tire pressures and uses a standard unit of pressure measurement. Options 2), 3), and 4) are incorrect, as they represent kPa, bar, and mmHg units, respectively, and are not typically used for this purpose.