Final answer:
Ingrown hairs can be caused by improper shaving techniques, dry skin, tight clothing, and curly or coarse hair texture, all of which contribute to the risk of hair re-entering or getting trapped under the skin.
Step-by-step explanation:
All of the following may cause ingrown hairs: A) Improper shaving techniques, B) Dry skin, C) Tight clothing, D) Curly or coarse hair texture. These factors can contribute to the occurrence of ingrown hairs by either promoting the curling back or sideways growth of hair into the skin or creating a favorable environment for hairs to get trapped under the skin. Improper shaving can lead to hair tips becoming sharp and more likely to re-enter the skin. Dry skin can cause a buildup of dead skin cells that block the hair follicle's exit.
Tight clothing can result in physical pressure that alters the direction of hair growth, and curly or coarse hair naturally has a higher tendency to grow back into the skin. To prevent ingrown hairs, it is recommended to use proper shaving techniques, moisturize the skin, wear looser clothing, and be mindful of one's hair texture when grooming.