Species - area relationship in South American jungles was studied by-

The correct answer is Option (1) → Alexander von Humboldt

Option (1) Alexander von Humboldt — Correct. He found that species richness rises with the area explored, but only up to a limit.

NCERT Extract:
Patterns of Biodiversity – “… During his pioneering and extensive explorations in the wilderness of South American jungles, the great German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.”