Please choose the correct ending to complete the given sentence: Youth: [header] How to reduce blackheads [title] Do not pick the blackheads or try to squeeze them out. [step] This increases the likelihood of an infection and scarring. Instead, try blackhead removal strips.

Ending1: These strips are professional and are fda approved, as they have been shown to be effective for skin, but may cause " cracks " on the skin if you pick them. [substeps] These strips are considered to be safe for children and you should also avoid picking or squeezing blackheads on your face and hands. Ending2: [substeps] These strips contain salicylates and papillons that kill the adult cells responsible for making blackheads. As such, you should only use your fingertips to pick blackheads. Ending3: [substeps] These adhesive strips stick to your skin and when you pull them off, the blackheads should stick to the strip. The strips work best for small blackheads, but they do not work very well for larger or deeper ones. Ending4: These strips are strips that stay in place after four or five days. [substeps] This method can produce longer or shorter blackheads.

Answer format: ending1/ending2/ending3/ending4