I think it is C, because if I'm right present principal is something that is happening presently? If so, C would be the answer because they "are doing" the exercises right now in context.
The best option is D studied.
This word denotes a measured, even-handed approach to the issue. So, it should be :Current immigration policy must be studied before new proposals can be made.
THAT MOST MEDIA ISNT TRUE
Answer:
A, nouns
Explanation:
starvation, construction, etc they form verbs to nouns