Answer:
i believe he was about 42.
Explanation:
The answer is D.
"Keep", "factor", and "calculate" are all verbs in the list of things the new system allows teachers to do. The other sentences are inconsistent with their list of verbs/adjectives/nouns. Thus, option D is the only one that is grammatically correct.
I am not too good at explaining, so let me know if you are still confused.
Hope this helps! :)
Explanation:
Although Jack London gained fame with his vivid short stories, establishing himself as a master of the short form, his best-known work is a novel named The Call of the Wild. This novel is required reading in many classrooms.