Answer:
1. Vertical
2. We can't determine with the horizontal line test.
Step-by-step explanation:
A function is a relation where each value of x is related with only one value of y.
We can also say that a graph is a function if when we draw a vertical line, the line only crosses the graph once.
So, the line that doesn't represent a function is the vertical line and we can't determine whether a graph represents a function with the horizontal line test.