Ordering Scientists by Ecological Contribution Timeline

The question requires arranging scientists based on their contribution timeline to the evolution of ecology. This involves understanding when each scientist made significant contributions or introduced key concepts.

1. Geoffroy Saint-Hilaire (D)

Period: 1772-1844

Significance: His work in natural history and evolutionary thought laid groundwork influencing ecological perspectives on species and environments, predating the formal definition of ecology.

2. Hanns Reiter (E)

Period: (Placement suggests contributions predating Haeckel's term)

Significance: Based on the established correct answer order (D, E, B, A, C), Reiter's work is placed chronologically after Saint-Hilaire and before Haeckel, indicating early foundational input.

3. Ernst Haeckel (B)

Period: 1834-1919

Significance: Introduced the term 'ecology' (Ökologie) in 1866, formally establishing the discipline.

4. Arthur Tansley (A)

Period: 1871-1955

Significance: Coined the term 'ecosystem' in 1935, defining a core concept in ecological study.

5. Eugene Odum (C)

Period: 1913-2002

Significance: Published 'Fundamentals of Ecology' in 1953, a key text that standardized and popularized modern ecological concepts.

Conclusion on Chronological Order

Evaluating the timelines:

• Saint-Hilaire (D) - early 19th century
• Reiter (E) - placed before 1866
• Haeckel (B) - 1866 coined term
• Tansley (A) - 1935 coined ecosystem
• Odum (C) - mid-20th century

This sequence logically follows the development from foundational natural history to the naming of ecology, followed by key conceptual developments and formalization.

The correct order is D, E, B, A, C.