The chile that is considered to be the mildest among the options you provided is B) Poblano.
Here's a brief comparison of the heat levels:
- Serrano peppers are generally medium-hot.
- Jalapeño peppers are also medium, but can be a bit hotter than poblano.
- Poblano peppers are relatively mild, typically measuring around 1,000 to 2,000 Scoville heat units (SHU).
So, in terms of mildness: Poblano < Jalapeño < Serrano.