Among living birds, which species lays the largest egg in the world in terms of overall size and volume?

Introduction / Context:
This question is a classic from animal records in general knowledge. Many exams ask about the largest, smallest, heaviest or fastest animals. Here the focus is on the bird that lays the largest egg among living bird species. Knowing this record helps in answering multiple questions related to comparative biology and animal world superlatives.

Given Data / Assumptions:

• The question is limited to living birds, not extinct ones like dinosaurs.
• It asks for the species that lays the largest egg in terms of size and volume.
• The options include large birds like eagle, ostrich, vulture, owl and albatross.
• We assume the question follows the standard record presented in common GK books.

Concept / Approach:
Ostrich is the largest living bird and also lays the largest egg among living bird species. An ostrich egg is much larger than eggs of eagles, owls or vultures. While some other birds lay relatively large eggs compared to their body size, in absolute terms the ostrich egg is the largest. Therefore, when a question asks for the largest egg laid by any living bird, the correct answer is ostrich, a fact repeated in most general science and GK reference books.

Step-by-Step Solution:
Step 1: Recall that ostrich is the heaviest and tallest living bird. Step 2: Connect this with the idea that larger birds usually lay larger eggs in absolute terms. Step 3: Compare ostrich with other options such as eagle, owl and vulture, which are large but still much smaller than ostrich. Step 4: Remember that albatross, though large, lays eggs smaller than those of ostrich when compared directly. Step 5: Based on these comparisons, choose ostrich as the bird that lays the largest egg among living birds.

Verification / Alternative check:
You can confirm this from any standard table of animal records, which typically lists ostrich as both the largest living bird and the layer of the largest bird egg. Photographic comparisons in science books and documentary programmes also show the very large size of ostrich eggs relative to those of other birds. This consistency across references confirms that ostrich is the correct answer here.

Why Other Options Are Wrong:
Eagle lays eggs that are large compared to small birds but significantly smaller than ostrich eggs.
Owl species are mostly medium sized birds, and their eggs are nowhere near the size of an ostrich egg.
Vulture eggs are bigger than many bird eggs but again do not approach the size and volume of an ostrich egg.
Albatross lays relatively large eggs as a big seabird, yet in absolute dimensions these are smaller than ostrich eggs.

Common Pitfalls:
Students sometimes confuse largest bird overall with bird having the largest egg relative to body size. For relative size, kiwi is an important example, but for absolute largest egg, ostrich holds the record among living birds. Another pitfall is to be misled by impressive raptors like eagles, assuming size of prey equals size of egg, which is not correct. Keeping the distinction between absolute and relative egg size clear will help in answering similar questions correctly.

Final Answer:
The living bird that lays the world's largest egg is the ostrich.