Given the task definition and input, reply with output. 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 tryptic soy agar (tsa ) [title] Using the marker and tape label the flask with your name, the date and the name of the solution (tsa). [title] Carefully slide the large magnetic stir-bar into the erlenmeyer flask. [title] Measure 500 ml of distilled water with the graduated cylinder. <sep> (A) [title] Once the mixture is properly mixed, insert the acetic nut into the chamber of the flask, and lift out the lid of the syringe. [title] Thread the brush of the winding mechanism through the locking piece and plug the cap on. (B) [title] Pour 500 ml of distilled water from the graduated cylinder into the erlenmeyer flask. [title] Place metal cap on the flask. (C) [step] Be careful not to let the water float in the flask. [title] Put measured percentage of the liquid into the flask. (D) [title] Add five teaspoons of corn syrup into the end of the stirring device. [title] Close the swirl cap on the stir bar.
B