Answer: First option.
Step-by-step explanation:
You know that the product obtained by multiplying a binomial and a trinomial is:

Then, in order to simplify this product, it is necessary to add the like terms.
Therefore, the expression that is equivalent to this product after it has been fully simplified is:

You can observe that this matches with the first option.
1 gallon = 7 miles
2 gallon = 14 miles
3 gallon = 21 miles
4 gallon = 28 miles