Which of the following is NOT a common type of eyelash extension material?

The correct choice is the one that identifies wood as not a common type of eyelash extension material. Eyelash extensions are typically made from materials that can provide a natural look, flexibility, and durability, which is why synthetic, silk, and human hair are popular options.

Synthetic materials are designed to mimic the natural appearance of eyelashes while offering various lengths and thicknesses. Silk extensions are known for their soft feel and light weight, making them comfortable to wear while enhancing the eyes' beauty. Human hair lashes provide a very natural look and can be styled similarly to natural eyelashes.

Wood, however, is not suitable for eyelash extensions due to its rigid and non-flexible nature. It lacks the necessary properties to mimic the softness and movement of natural eyelashes, making it impractical for this application. Additionally, using wood in this context would pose a risk of irritation or injury, since it's not designed for direct contact with the sensitive eye area. Thus, wood is not a valid material used in eyelash extensions.