You will be given a definition of a task first, then some input of the task.
In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to make english muffins or bread [title] Make a sourdough starter. [step] Combine 2 1/2 cups of flour, one packet of yeast, and 2 cups of warm (90-110f) water in at least a 8 cup bowl. Mix with a spoon until it is a smooth batter. <sep> (A) Spread 1 cup extra-sweet and/or spring-loaded yeast flour into the dough. Use your fingers to form a dough ball and set it aside, laying it out on clean, cool, and level surface. (B) [substeps] Make sure the batter isn't too thick, as it could clog the muffin pans on your way home. [title] Stir the yeast and condensed milk until the mixture is sticky. (C) This will sit and " cook " for at least 4 hours during which time it will increase in volume a lot (hence the big bowl). Cover with some plastic wrap or a cloth and leave in a warm place (room temperature is fine). (D) [substeps] You can choose your type of sourdough starter mix, as well. You can use a clay mix, a matte one, or something else.
Output:
C