14.The word "constituents"in line 7is closest in meaning to

(A)relatives

(B)causes

(C)components

(D)targets

15.Why does the author mention "cosmic rays't'in line 7?

(A)As part of a list of things containing helium

(B)As an example of an unsolved astronomical puzzle

(C)To explain how the universe began

(D)To explain the abundance of hydrogen in the universe

16.The word "vary"in line 10is closest ill meaning to

(A)mean

(B)stretch

(C)change

(D)include

17.The creation of helium within stars

(A)cannot be measured

(B)produces energy

(C)produces hydrogen as a by-product

(D)causes helium to be much more abundant In old stars than In young star:

18.The word "calculated"in line 15is closest in meaning to

(A)ignored

(B)converted

(C)increased

(D)determined

19.Most of the helium in the universe was formed

(A)in interstellar space

(B)in a very short time

(C)during the first minute of the universe's existence

(D)before most of the hydrogen

20.The word "ceased"in line 26is closest in meaning to

(A)extended

(B)performed

(C)taken hold

(D)stopped