Final answer:
The amount of roux needed for medium consistency per gallon is closest to option 3, which is "1 gallon". Traditionally, a medium roux is made with an equal weight of fat and flour, where one pound (or 16 ounces) of each is used per one gallon of liquid, summing to approximately 32 ounces per gallon.
Step-by-step explanation:
The question is asking about the proper amount of roux needed on a per-gallon basis to achieve medium consistency. To answer this, we will convert between ounces and gallons using customary standard weights and liquid measurements.
Knowing that a gallon is equal to 128 fluid ounces, we can understand that option 3, "1 gallon", is the correct answer. This is because medium consistency roux generally requires an equal weight of fat and flour, which is commonly 1 pound of each per 1 gallon of liquid, and since 1 pound of flour or fat is approximately 16 ounces, the consistent amount for a medium roux would be approximately 32 ounces (16 ounces of flour plus 16 ounces of fat) per gallon of liquid. However, standard recipes for roux could vary and may not strictly adhere to a 32-ounce rule.