Final answer:
The standard AHRI 'A' design condition used for rating unitary air conditioning equipment is 75°F indoor dry-bulb and 60°F indoor wet-bulb.
Step-by-step explanation:
The standard AHRI 'A' design condition used for rating unitary air conditioning equipment is 75°F indoor dry-bulb and 60°F indoor wet-bulb (option c). This condition represents the average expected indoor temperature and humidity for comfort cooling applications.
By using this design condition, manufacturers can rate their air conditioning equipment based on its performance under typical operating conditions, ensuring that the equipment can maintain comfortable indoor conditions for occupants.
For example, a unitary air conditioning system rated at this condition should be able to cool a space to 75°F with a relative humidity of 50%.