What is the best description of the process that occurs in the starter to give sourdough its famous tangy flavor?

The answer is explained below.

Explanation:

Sourdough bread is made by the fermentation of dough. Lactobacilli and yeast are an important part of this process. The flavor comes from lactic and acetic acids, which are produced by the bacteria in the environment, and that is where lactobacilli and yeast are very important.

The sour flavors come from lactic and acetic acids produced by inevitable environmental bacteria, which are working on the flour's sugars along with the yeast. Different bacteria make different sour flavors