Explanation:

- Here’s the thing—Johann Dobereiner was the chemist who spotted that certain groups of three elements (he called them “triads”) like lithium, sodium, and potassium, had similar properties. He showed that the properties of the middle element were kind of an average of the other two.

- Lothar Meyer worked on plotting atomic volumes and contributed to early versions of the periodic table, but not the triad patterns.

- John Newlands suggested the “Law of Octaves,” noticing every eighth element had similar properties, but didn’t focus on triads.

- Dmitri Mendeleev built the modern periodic table, getting famous for predicting new elements, but triads weren’t his main contribution.

So, yeah, your answer is option 1 – Johann Dobereiner.