Of the following beer styles, which would have the lowest alcohol content?

Best Bitter is the correct choice for having the lowest alcohol content among the listed beer styles. This style typically has an alcohol by volume (ABV) range of about 3.2% to 5.0%.

Best Bitter is traditionally brewed to be a sessionable ale, meaning it is designed for easier drinking over longer periods without overwhelming the palate with higher alcohol levels. The focus for this style is on balance and drinkability, often featuring a moderate malt sweetness balanced with hop bitterness.

In contrast, the other styles listed tend to have higher ABV ranges. American Porters usually range from about 4.0% to 7.0%, Oatmeal Stouts can range from approximately 4.0% to 7.0% as well, and Wee Heavy, which is a strong Scotch ale, typically has a substantial higher alcohol content that can range from 6.5% to over 10%. Each of these styles is intended to provide a richer and often more complex flavor experience that typically requires higher alcohol levels to balance the richer malt profiles.

Therefore, Best Bitter is distinctly recognized for its moderate and sessionable alcohol content, making it the lowest among the choices provided.