Answer:
e. not being so
Step-by-step explanation:
This is the section of the sentence that needs to be changed in order to make the sentence more correct. The phrase "not being so" does not match the way the rest of the sentence is written. A way in which we could change this section and make the sentence correct would be:
"The spies started to empathize with the man they were watching, and suddenly they wondered if their actions were morally excusable or not."
This sentence expresses the same ideas as the previous one, but is a lot clearer for the reader.