To establish the proportional relationship between inches and feet from the information given, we first note that there are 12 inches in 1 foot. Thus, to express the relationship mathematically, we can write:
\[ \text{Inches} = 12 \times \text{Feet} \]
If we represent the inches (y-axis) as y and the feet (x-axis) as x, the equation can be rewritten as:
\[ y = 12x \]
Thus, the correct answer is:
D. y = 12x