Answer:
C. 2 times the number of pages in the book
Explanation:
Are these the choices?
A. 15 years of schooling
B. 60 seconds multiplied by 5
C. 2 times the number of pages in the book
D. 3 dollars and 76 cents
If so, then the answer is C.
The number of pages in the book is not known and depends on which book it is, so twice that amount is also an unknown changeable quantity.