Direct object is D. A NOUN, PRONOUN, OR WORD GROUP THAT RECEIVES THE ACTION OF THE VERB.
Direct object follows a transitive verb (action verb) not a linking verb. It is always placed after the verb not before it. It receives the action not modifies the action verb.
I think that the answer is B.
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Answer: D. The article will show how the island people are fighting greenhouse gas.
Explanation: The article addresses the topic of the alarming damages that greenhouse gas is making to the environment. In the final part of the paragraph, the author mentions that only a small amount of these gases come from the Pacific islands and that the rest comes from other countries. Therefore; to call an action in the matter, the article will probably inform the reader of the struggles the people of the Island go through, and how they try hard on fighting this issue so that it raises awareness.