Final answer:
Stage 1 of the demographic transition theory is identified by very high birth and death rates leading to a stable population size, typical of a pre-industrial society.
Step-by-step explanation:
According to demographic transition theory, the stage marked by very high birth and death rates is Stage 1. This is the initial stage of the demographic transition, where a country or a region is characterized as a rural pre-industrial society. In Stage 1, both birth and death rates are high, which results in a stable population size. Life expectancy during this phase is relatively short, and infant mortality rates are high, due to limited access to modern medicine and poor living conditions. A historical example of this stage would be the United States in the 1800s.
The Demographic Transition Model (DTM) serves as a multistage model that shows how countries transition from high birth and death rates to lower ones as they undergo industrialization and development. Eventually, societies move into Stage 4 and potentially Stage 5 of the DTM, where birth and death rates are much lower, leading to a stable or declining population.