Question

1. what is the most effective way to combine sentences 19, 20, and 21?

the idea of eating cereal for breakfast was promoted by the late 1800s by john kellogg and charles post the two men we now recognize as big names in breakfast cereal.

although the idea of eating cereal for a healthy breakfast was being promoted in the late 1800s, john kellogg and charles post were recognized as two of the biggest names in cereal.

by the late 1800s, john kellogg and charles post, who we now recognize as two of the biggest names in breakfast cereal, promoted the idea of eating cereal for health.

Explanation:

To determine the most effective sentence combination, we analyze clarity, logical flow, and accurate information. The third option ("By the late 1800s, John Kellogg and Charles Post, who we now recognize as two of the biggest names in breakfast cereal, promoted the idea of eating cereal for health.") correctly structures the time, the people (with a descriptive clause), and the action (promoting cereal for health) without introducing errors or confusing relationships, unlike the other options which have issues like passive voice awkwardness or illogical connections.

Answer:

The third option: By the late 1800s, John Kellogg and Charles Post, who we now recognize as two of the biggest names in breakfast cereal, promoted the idea of eating cereal for health.