Which graph represents a function with a rate of change of 0.5? On a coordinate plane, a line with negative slope goes through points (negative 1, 1) and (0, negative 1). On a coordinate plane, a line with negative slope goes through points (negative 2, 0) and (0, negative 1).

Interpreting as: Which graph function
Input interpretation:
Which (Wolfram Language symbol) | Graph (Wolfram Language symbol)

Usage:
Which
Which[test1, value1, test2, value2, ...] evaluates each of the testi in turn, returning the value of the valuei corresponding to the first one that yields True.

Graph
Graph[{e1, e2, ...}] yields a graph with edges ej. Graph[{v1, v2, ...}, {e1, e2, ...}] yields the graph with vertices vi and edges ej. Graph[{..., wi[vi, ...], ...}, {..., wj[ej, ...], ...}] yields a graph with vertex and edge properties defined by the symbolic wrappers wk.

Timeline:

Yes i could be the length of the triangle