Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to grow bacteria in a petri dish [title] Prepare the agar. [step] Agar is the jelly-like substance used to culture bacteria. It is made from a type of red algae, which provides an ideal growing surface for many different types of bacteria.

Ending1: Some types of agar contain added nutrients (such as sheep's blood) which help to promote more vigorous bacterial growth. [substeps] The easiest type of agar to use for this experiment is a nutrient agar which comes in powder form. Ending2: The agar helps the petri dish's water to become warm, filtered, and even emulsified by the bacteria. [substeps] Peel and core 1 large carton of agar and add 2 cups water to a saucepan over medium heat. Ending3: To prep the agar, you will need to mix your agar. Pour the agar into your petri dish. Ending4: Either buy a blender or food processor to cut it into tablets. [substeps] The food processor will push the agar to the main counter, and then short through turning it into a paste.

Answer format: ending1/ending2/ending3/ending4