This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to clean a cast iron sink
Mix water and dishwashing soap together in a 5-gallon (18. 92 l) bucket.
Mix 1 gallon (3.78 l) of hot water with 2 tablespoons (29.57 ml) of dishwashing soap. Look for a dishwashing liquid that has a grease cutting agent in it and a scent that you like.

Pick from:
[1]. You should also add about cup (120 ml) of baking soda and 1 cup (240 ml) of dish soap. Do not use baking soda or dish soap as these are environmentally admissible ingredients.
[2]. Turn on the tap until it reaches a boil. Add 1 tablespoon (14.
[3]. Wipe down the sink with a sponge or rag. Dip a sponge or rag into the water and soap solution that you created.
[4]. Mild dish detergent will work just fine. Too strong of a flavor could make your sink tough.
The answer is:
[3].