Meaning: 'Capable' means having the ability or power to do something, indicating that these organisms can perform photosynthesis.

Wrong options:

• aware: 'Aware' means having knowledge or perception of a situation, which does not fit the context of performing a biological process like photosynthesis.
• proud: 'Proud' refers to a feeling of deep pleasure or satisfaction, which is irrelevant to the ability to perform photosynthesis.
• guilty: 'Guilty' implies a sense of responsibility for a wrongdoing, which is not applicable in this context.

Correct answer: convert

Explanation: The word 'convert' is appropriate as it describes the process of changing carbon dioxide and water into carbohydrates, which is the essence of photosynthesis. It fits both grammatically and contextually within the sentence.

Meaning: 'Convert' means to change something into a different form or properties, specifically referring to the transformation of substances in photosynthesis.

Wrong options:

• communicate: 'Communicate' means to share or exchange information, which does not relate to the process of photosynthesis.
• build: 'Build' implies constructing something, which is not the precise action taken during photosynthesis, as it involves transformation rather than construction.
• force: 'Force' means to make something happen against its will, which does not accurately describe the natural process of photosynthesis.

Correct answer: complex

Explanation: The word 'complex' is suitable as it describes the nature of the organic compounds produced by autotrophs, which are more intricate than simple carbohydrates. This aligns with the context of the sentence discussing the products of photosynthesis.

Meaning: 'Complex' refers to something that is made up of many interconnected parts, indicating that the organic compounds are not simple but rather intricate and multifaceted.

Wrong options:

• normal: 'Normal' suggests something that is standard or typical, which does not convey the idea of the advanced nature of organic compounds produced.
• authentic: 'Authentic' means genuine or real, which does not accurately describe the complexity of the organic compounds in this context.
• futile: 'Futile' means pointless or ineffective, which contradicts the productive nature of the organic compounds created by autotrophs.

Correct answer: referred

Explanation: The word 'referred' fits grammatically and contextually as it indicates how the autotrophic segment is commonly named within ecological discussions. It aligns with the formal tone of the text.

Meaning: 'Referred' means to mention or allude to something, indicating that this segment of the ecosystem is commonly known by a specific term.

Wrong options:

• made: 'Made' implies creation, which does not fit the context of naming or identifying a segment of the ecosystem.
• known: 'Known' suggests familiarity but does not convey the act of naming or referring to something, which is more precise in this context.
• provided: 'Provided' means to supply or furnish, which does not align with the context of how the autotrophic segment is identified.