Question Type: Biology/Knowledge-based

Step-by-step solution:

Holozoic nutrition is a type of nutrition where organisms ingest solid organic matter and digest it internally. The process involves several steps: ingestion, digestion, absorption, assimilation, and egestion.

• Ingestion: The intake of food into the body.
• Digestion: The breakdown of food into simpler, absorbable molecules.
• Absorption: The uptake of digested nutrients into the bloodstream.
• Assimilation: The incorporation of absorbed nutrients into the body's tissues and cells.
• Egestion: The removal of undigested waste from the body.

For complex organisms practicing holozoic nutrition, the very first step is always ingestion—taking food into the body. Without ingestion, there's no food to digest, absorb, assimilate, or egest.

Why other options are incorrect:

• Egestion is the final step, the removal of waste.
• Absorption occurs after digestion.
• Assimilation takes place after absorption.

Therefore, the correct answer is ingestion.