All of them except for the 3rd sentence are correct :)
None of these words are underlined.
Answer:
I would say "Chips and cookies are high in fats and sugars which increases the risk of obesity.", because it is a direct cause of the problem, student obesity. :)
Answer: To provide reasons why he decided to speed up the nation's efforts to be first in space.
Explanation: Here~! <3





sorry I don't know about 15, 16 and 20th question