The author mentions professor hodous's 16 years of missionary service in china primarily to

demonstrate that professor hodous is committed to treating buddhism fairly
indicate why professor hodous should be considered an expert on buddhism
point out that professor hodous has a religious bias regarding buddhism
show that professor hodous is a deeply religious person

The answer is: indicate why Professor Hodous should be considered an expert on Buddhism

Explanation:

When learning an educational book on a certain topic, it is essential to be familiar with the author's level of expertise, in order to gain valid information. One's level of expertise can be judged based on his knowledge or experience. Although undoubtedly immense, we can not draw definite conclusions about the range of professor's knowledge from this excerpt. However, from the information about his sixteen years long missionary services in the important Buddhism center, we can certainly claim that professor Hodous is filled with experience on this topic.

irving effectively uses emotional responses to create suspense in the story.irving’s tone creates expectations for the reader, which in turn create suspense.irving’s suspense would have been more effective with more vivid details.irving’s story is not suspenseful

they insisted that there was not enough time to learn everything.  

explanation:

if they were going to steal the answers that is simply because they insisted that there was not enough time to learn everything.