Final answer:
An acceptable combination of conduit bends between pull points according to the NEC is option b: Two 45-degree bends, which is practical and below the maximum total sum of angles allowed.
Step-by-step explanation:
The correct answer to the question of which combination of conduit bends between pull points is acceptable is option b: Two 45-degree bends. The National Electrical Code (NEC) generally limits the total sum of angles between pull points to a maximum of 360 degrees. Therefore, options with bends totaling more than 360 degrees, such as a 90-degree bend followed by a 180-degree bend and three 90-degree bends, are not acceptable. Likewise, while a 180-degree bend followed by a 90-degree bend does not exceed the limit, it is impractical and could make pulling wires very difficult due to the sharp angles. So, two 45-degree bends, totaling 90 degrees, is not only permissible but also practical for wire installation.