Answer:
2.) undefined slope 3.) zero slope (i'm not sure what 1 and 4 are, sorry!)
Step-by-step explanation:
undefined slope has the same x-coordinate and the denominator becomes 0. it also is a vertical line. for a zero slope, it has the same y-coordinate and the numerator is 0. this is a horizontal line. *this is my first response so if i am wrong, that is embarrassing*