The correct answer is option 2. Crude oil is sometimes termed sweet because it has a low sulfur content. Sulfur is a compound that contributes to a sour taste, so when crude oil has less sulfur, it is considered to have a mild or sweet taste.

Option 1 is incorrect because crude oil does not contain sugars, so it does not taste sweet in a literal sense.

Option 3 and option 4 are unrelated to the sweetness of crude oil. The acidity or alkalinity of crude oil has no effect on its taste.

Therefore, the answer provided in the question is generally correct, and there is no alert or correction needed.