Please choose the correct ending to complete the given sentence: Computers and Electronics: [header] How to make aloe vera shampoo [title] Obtain organic aloe vera gel from a health or natural medicine shop. [step] Commercially available aloe vera gel is sold in bottles and they come in varying degrees of purity. Many of these commercial products contain additives and chemicals.

Ending1: [title] Clean 1 gallon (3.8 l) of aloe vera gel. [step] Pour 1/2 of the gel into a clean sink or dish and rinse off with cold water. Ending2: Ask the pharmacist or health care professional what they recommend for the specific product you want to get ready for your shampoo. [substeps] Organic products including aloe vera gel contain phenols and sulfates which can irritate your scalp. Ending3: Since you'll be using this shampoo directly on your hair and scalp, it's best to get the purest aloe vera gel you can find. Check the label and ingredients before you buy a product. Ending4: [substeps] Make sure to wear gloves when handling any aloe vera gel as it might contain potentially harmful chemicals. If you acquire aloe vera gel-containing additives use caution and take a whiff-test to avoid potentially harmful ingredients.

Answer format: ending1/ending2/ending3/ending4