Chronology of Population Theories

To determine the correct chronology, we need to establish the approximate timeframes for the key contributions of each theorist regarding population:

• T.R. Malthus (C): Famous for his 'Essay on the Principle of Population', first published in 1798. This is the earliest significant theory among the options.
• Karl Marx (A): Critiqued Malthus's theories. While his major works like 'Das Kapital' were published later (Vol. 1 in 1867), his ideas on population were developed throughout the mid-to-late 19th century.
• Edwin Cannan (B): An economist who discussed population theories, often building upon or critiquing earlier ideas, including Marx's. His significant economic writings, touching upon population, occurred in the late 19th and early 20th centuries (e.g., 'Wealth', 1914). He generally follows Marx chronologically in terms of theoretical development in this context.
• C.R. Blacker (D): His notable work, 'The ABC of Population Control', was published in 1938, placing him last chronologically among these theorists.

Established Chronological Order

Based on the publication and development periods:

1. T.R. Malthus (C) - 1798
2. Karl Marx (A) - Mid-to-late 19th Century
3. Edwin Cannan (B) - Late 19th/Early 20th Century
4. C.R. Blacker (D) - 1938

Therefore, the correct chronological sequence is C, A, B, D.