Answer:
A.
![y=(1)/(4)x](https://img.qammunity.org/2020/formulas/mathematics/high-school/nt6riq67ihrwtxmjq41hrv74710pba0to3.png)
Explanation:
The Direct Proportionality equation is: f (x) = k.x, where k is the proportionality constant and f (x) is y.
So y = k.x is the mathematical formula or model.
The graphical representation of the direct proportionality function is a line that passes through the origin of coordinates.
In the given case, we must calculate the value of k and then replace it in the formula, being
y = 3
x = 12
k =?
If y = k.x, isolating k is obtained
![k=(y)/(x)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/k3udmoohkeqhw599yc73nqw67cmif8a8rn.png)
![k=(3)/(12)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/hzl5tzsy7z6mcaj9eqt3oik0pnwqiddqdq.png)
Expressing the fraction in its simplest form, we have
![k=(3/3)/(12/3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ujy8k2yscs7pk6clsy9jyrz95kcapgm031.png)
![k=(1)/(4)](https://img.qammunity.org/2020/formulas/mathematics/high-school/e6ecgwirlgnnun5qpkpmq6n6526zzc50zp.png)
Substituting that value in the original formula y = k.x, we have
![y=(1)/(4)x](https://img.qammunity.org/2020/formulas/mathematics/high-school/nt6riq67ihrwtxmjq41hrv74710pba0to3.png)
Hope this helps!