Verification of truth: Which statement is true for all animals? Select the attribute that every animal necessarily possesses.

Introduction / Context:
This item tests biological generalization: identify a property that applies to all animals, without exceptions created by species diversity or developmental differences.

Given Data / Assumptions:

• “Animals” covers the entire kingdom Animalia.
• We seek a universal attribute across taxa.

Concept / Approach:
Many morphological traits vary (eyes, legs, horns), but behavioral drives (innate patterns aiding survival and reproduction) are present across animal taxa. “Instincts” (innate behavioral tendencies) exist in vertebrates and invertebrates alike.

Step-by-Step Solution:

Verification / Alternative check:
Consider basal animal lineages: even simple animals display innate response patterns (taxis, reflexes), aligning with “instincts.”

Why Other Options Are Wrong:

• Eyes/Four legs/Horns: counterexamples exist.
• None of these: incorrect because instincts are universal.

Common Pitfalls:
Overgeneralizing from common domestic species to all animals.

Final Answer:
Instincts