Step 1 — Read the sentence carefully:
"The influence of the environment on man is revealed by an _____ study."
The blank requires a word that connects the environment with its relationship to human beings.
Step 2 — Interpret the clue:
The key phrase is "influence of the environment on man." This points toward the branch of study that deals with the interaction between living beings and their surroundings.
Step 3 — Meaning of the correct word:
The word ecological relates to ecology, which is the scientific study of how organisms, including humans, interact with each other and with their environment.
Step 4 — Fit the word into the sentence:
"The influence of the environment on man is revealed by an ecological study." This makes clear sense because ecology directly examines the effect of environment on living beings.
Final Answer:
The correct option is (B) : ecological.