B
Step-by-step explanation:
Choose any point and put it into one of the choices of equations. Let's just do (4, 2):
A) y = 2x  ⇒  2 =? 2 * 4  ⇒  2 ≠8  ---  eliminate
B) y =1/2x  ⇒  2 =? 4 * (1/2)  ⇒  2 = 2  ---  correct; keep it
C) y = 1/2 + x  ⇒  2 =? 1/2 + 4  ⇒  2 ≠4.5  ---  eliminate
D) y = 2 + x  ⇒  2 =? 2 + 4  ⇒  2 ≠6  ---  eliminate
Thus, B is the correct answer.
Hope this helps!