Which of the following is classified as a sunscreen ingredient?

Octyl methoxycinnamate, also known as ethylhexyl methoxycinamate or octinoxate, is an organic compound widely used in sunscreen formulations as a UV filter. Its primary function is to absorb UVB radiation, helping to protect the skin from damage caused by sun exposure. This active ingredient plays a vital role in photoprotection, making it essential in products designed to prevent sunburn and long-term skin damage.

Sodium bicarbonate, citric acid, and petrolatum do not serve as effective sun protection agents. Sodium bicarbonate is primarily used as a buffering agent or for its antacid properties, citric acid is commonly found in food and skincare products for its exfoliating and pH-adjusting capabilities, and petrolatum is a moisturizer rather than a sunscreen. Thus, octyl methoxycinnamate stands out as the only ingredient among the options provided that is specifically classified as a sunscreen ingredient due to its protective properties against UV radiation.