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! :)
Answer:
A product aimed at an audience of teenagers would show that the product is aimed squarely at the lifestyle needs of teenagers.
Explanation:
Give an introductory but also use something catchy. personally, I'd says something like "My name is _____. it's an interesting name that you don't hear often. _____ means.." and so on.
