Which sweetener, first used in 1879, has received FDA approval for use in fruit juice beverages?

The correct option is Saccharin.

Step-by-Step Explanation:

1. Discovery and History:
Saccharin is one of the oldest artificial sweeteners. It was discovered in 1879 by chemists Constantin Fahlberg and Ira Remsen at Johns Hopkins University while researching coal tar derivatives.

2. Regulatory History and FDA Approval:
Over the decades, saccharin's safety was extensively evaluated by health organizations worldwide. The U.S. Food and Drug Administration (FDA) approved saccharin for use as a sweetener in various foods and beverages, including processed food products, fruit juice beverages, and as a tabletop sweetener.

3. Comparison with Other Sweeteners:
- Aspartame: Discovered much later in 1965.
- Sucralose: Discovered in 1976.
- Neotame: Developed in the late 20th century and approved by the FDA in 2002.

Thus, based on its discovery date of 1879 and subsequent FDA approvals for food and beverage applications (including fruit juice beverages), Saccharin is the correct answer.