Final answer:
The ingredient in shampoo that is responsible for cleaning oily dirt is surfactants, with common examples being sodium lauryl sulfate and sodium laureth sulfate.
Step-by-step explanation:
The ingredient in shampoo that attracts oily dirt in hair and washes it away is surfactants. Surfactants are chemical compounds that are able to interact with both nonpolar substances, like oil and grease, and polar substances like water. This dual nature allows surfactants to emulsify oily dirt so it can be rinsed away. Shampoos commonly contain surfactants such as sodium lauryl sulfate or sodium laureth sulfate, which are effective in reducing the water's surface tension and improving wetting, thus enhancing the shampoo's ability to clean hair.