Which condition is likely to raise the load on an air conditioning system?

A 90-degree outdoor dry bulb temperature would indeed raise the load on an air conditioning system. When outdoor temperatures are higher, the air conditioning unit has to work harder to cool the indoor environment. This is because the system must remove heat from the indoor air while simultaneously dealing with the increased heat load from the warmer outdoor air. As the outdoor temperature rises, the temperature difference between the inside and outside of the home decreases, making it more challenging for the system to effectively cool the space.

In contrast, a 70-degree outdoor dry bulb presents a lower heat load, which is more manageable for the system. A 65-degree indoor dry bulb indicates a cooler indoor environment that typically requires less work for the air conditioning system to maintain comfortable conditions. Lastly, a 50-degree wet bulb represents a low humidity level and cooler temperature that would also not contribute to increasing the system's workload. Therefore, the choice of 90-degree outdoor dry bulb aligns with conditions that demand more energy and effort from the air conditioning system.