System of equations help?

im stuck on this question

Use the following System of Equations to answer the following questions:
x + y + z = 5
2x – 5y + z = –4
z = 0

What would the best first step be?
Select one:
a. Use the method of elimination on the x variable.
b. Use the method of elimination on the y variable.
c. Eliminate the z variable into both equation 1 and 2.
d. Graph the three equations and hope for a solution