Number 12 thank you ASAP

Answer:
0
Step-by-step explanation:
A slope of a straight, horizontal line is 0 as it is not going up or down.
Answer:
B) 0
Step-by-step explanation:
When it is a straight horizontal line the slope is 0, and when it is a straight vertical line the slope is undefined.
y= ___ is slope of 0
x= ___ is slope of undefined