Demographic transition model was given by

The question asks about the originator of a fundamental concept in demography. The Demographic Transition Model (DTM), which describes the historical shift from high birth and death rates to low birth and death rates as a country develops, was first proposed by American demographer Warren Thompson in 1929. His work laid the groundwork for understanding population changes over time.

• J. Clarke: A geographer known for population studies, but not the DTM's originator.
• J.J. Spengler: A prominent economist and demographer, but not credited with the DTM.
• Trewartha: Glenn Trewartha was a geographer known for his climate classification and population geography, but not the DTM.

The distractors are other notable figures in related fields, but none originated the DTM.