The answer choices aren't real close together here, so we can estimate again. We want the ratio of Masai speakers to Turkana and Sambur combined. These are all Eastern Nilotic languages, so it's the Nilotic column we're interested in.

This tells us that there are 346,000 mother tongue Masai speakers in Kenya, or about 350,000.

The number of Turkana and Samburu mother tongue speakers is $\(297,000+106,000\)$ or about 400,000 .

The ratio we want is about $\(\frac{350,000}{400,000}\)$ or $\(\frac{35}{40}=\frac{7}{8}\)$ or $\(7: 8\)$.