Regarding one dimensional heat transfer, choose the correct statement

• A. Steady- f (x), Unsteady- f (x, t)
• B. Steady- f (x, t), Unsteady- f (x)
• C. Steady- f (x, y, t), Unsteady- f (x)
• D. Steady- f (y, z), Unsteady- f (y)