Final answer:
Dibutyl phthalate (DBP) is used as a plasticizer and ingredient in nail polish to improve its flexibility and durability.
Step-by-step explanation:
The correct answer is dibutyl phthalate. Dibutyl phthalate (DBP) is commonly used as a plasticizer in nail polish, helping to make it more flexible and less prone to cracking or chipping. It is added to the polish formulation to improve its consistency and facilitate easy application to the nails. DBP also helps to enhance the durability and longevity of the nail polish.
Learn more about Plasticizer in nail polish