In general classification of animals, which one of the following groups is composed of warm blooded (endothermic) animals that maintain a nearly constant body temperature?

Introduction / Context:
Warm blooded animals, also called endotherms, can maintain a fairly constant internal body temperature regardless of external conditions. This is an important concept in basic zoology and physiology. Among the major vertebrate groups, only some are warm blooded. This question asks you to identify which group in the options consists of warm blooded animals that regulate their body temperature internally.

Given Data / Assumptions:

• Warm blooded or endothermic animals can maintain a steady internal body temperature.
• Cold blooded or ectothermic animals depend more strongly on external temperatures.
• The options include reptiles, insects, amphibians, birds, and molluscs.
• Only one of these groups is completely and clearly warm blooded.

Concept / Approach:
In basic biology, birds and mammals are considered endothermic, warm blooded animals. They generate heat through metabolic processes and use insulation like feathers, fur, or fat to conserve heat. Reptiles, amphibians, fishes, insects, and most invertebrates are ectothermic, meaning their body temperature changes with the environment. Since mammals are not listed among the options, birds are the only remaining group that fits the definition of warm blooded animals.

Step-by-Step Solution:
Step 1: Recall that warm blooded animals include birds and mammals, while reptiles, amphibians, and most other groups are cold blooded.Step 2: Check the options: reptiles, insects, amphibians, birds, and molluscs.Step 3: Identify birds as the only endothermic group in this list.Step 4: Confirm that reptiles, amphibians, insects, and molluscs cannot maintain constant internal temperatures in the way birds do.Step 5: Select Birds as the correct option.

Verification / Alternative check:
Standard zoology textbooks classify vertebrates by temperature regulation: birds (class Aves) and mammals (class Mammalia) are endotherms. All the other vertebrate and invertebrate groups mentioned are ectothermic. Since mammals are not present in the list, birds stand out as the only warm blooded group. This matches the definitions taught in school level science and confirms the choice.

Why Other Options Are Wrong:
Option A: Reptiles are cold blooded; their body temperature largely follows environmental temperature.Option B: Insects are ectothermic invertebrates and do not maintain stable internal temperatures like birds.Option C: Amphibians are also cold blooded and strongly influenced by surrounding water and air temperatures.Option E: Molluscs (like snails and octopus) are invertebrates that are not warm blooded.

Common Pitfalls:
Some students mistakenly believe that reptiles or amphibians basking in the sun are warm blooded. In reality, they are using external heat to raise their body temperature. Another pitfall is thinking that any animal living in a hot environment must be warm blooded. To avoid these errors, remember the key: birds and mammals are the classic endotherms, while most other groups are ectothermic.

Final Answer:
The correct answer is Birds.