Sociologist: Climate and geology determine where human industry can be established.
Statements
Causal Difference-Maker (determine) Climate and geology have a big causal influence on where human industry can be established.
Causal Chain (always result in, bring about) Drastic shifts → migrations → intermingling in climate of ideas
Conditional (necessary) Rapid advances in civilization → Intermingling of ideas
Evaluate / Goal
Since we were provided with 1 ⇢ 2 ⇢ 3 chain, it's possible the answer will just be 1 ⇢ 3, .
There's an overlapping idea - intermingling of ideas. It connects climate instability with rapidly advancing civilization, so the correct answer might softly connect those two concepts.