The graphs of functions f(x) and g(x) = f(x) + k are shown: Graph of line f of x going through ordered pairs 0, 1 and 2, 6. Graph of line g of x going through ordered pairs 0, negative 1 and 2, 4. What is the value of k? a k = 2 b k = −2 c k = 1 d k = −1