In the following question, out of the four alternatives, choose the one which can be substituted as a single word for the description: "Animals that can live on land and in water."

Introduction / Context:
This one-word substitute question checks basic biology vocabulary that is frequently used in school level science and in English exams. The description given is "Animals that can live on land and in water." You need to identify the correct zoological term that describes such animals.

Given Data / Assumptions:

• Description: animals that can live on land as well as in water.
• We are dealing with habitat and mode of life.
• Options mention various animal related terms such as Anthropoid, Aquatic, Amphibian, Marsupial, and Reptilian.
• We assume standard school level classification of animals.

Concept / Approach:
In biology, animals that can live both in water and on land are called "amphibians". The word comes from Greek roots "amphi" meaning "both" and "bios" meaning "life", which together suggest "double life". Typical examples are frogs and salamanders, which can breathe and move in both environments. "Aquatic" means water dwelling only, "anthropoid" refers to human like apes, "marsupial" refers to pouch bearing mammals like kangaroos, and "reptilian" relates to reptiles, many of which are not truly double life animals in the same sense.

Step-by-Step Solution:
Step 1: Identify the key condition: the animal must be able to live both on land and in water.Step 2: Recall the biological class of animals that have this lifestyle, such as frogs and toads.Step 3: Connect these animals with the term "amphibian".Step 4: Compare with the options and see that "Amphibian" is present as option C.Step 5: Confirm that other options do not match the double environment idea.

Verification / Alternative check:
Think of an example: a frog starts its life as a tadpole with gills in water and later develops lungs and legs for life on land. Such animals clearly fit the double life concept. We commonly refer to frogs and salamanders as amphibians. If we consider "Aquatic", fish are aquatic but they cannot live on land. "Anthropoid" describes apes that are similar to humans and certainly do not live in water. So only "Amphibian" satisfies both parts of the description.

Why Other Options Are Wrong:

• Anthropoid: Refers to primates with human like features, such as chimpanzees and gorillas. They are not dual environment animals.
• Aquatic: Means water dwelling. It describes animals that live mainly or only in water, not those that also live on land.
• Marsupial: Refers to mammals that carry young in a pouch, such as kangaroos and koalas. Their special feature is the pouch, not dual habitat.
• Reptilian: Related to reptiles like snakes and lizards. Many reptiles are terrestrial or aquatic, but the term does not specifically mean animals that live in both environments.

Common Pitfalls:
Some students pick "Aquatic" because they remember that amphibians spend time in water. However, the question clearly says "on land and in water". The word "amphibian" encodes this double life, while "aquatic" focuses only on water. Make a habit of linking scientific terms with their roots and precise definitions, not with vague associations.

Final Answer:
The correct one-word substitute for animals that can live on land and in water is Amphibian.