Which of the following exhibits metagenesis
(a) Hydra
(b) Adamsia
(c) Aurelia
(d) Obelia

Options

A. Hydra
B. Adamsia
C. Aurelia
D. Obelia.

Answer

To solve the question regarding which organism exhibits metagenesis, we will follow these steps:

### Step 1: Understand the concept of metagenesis
Metagenesis refers to the alternation of generations in the life cycle of certain organisms, specifically involving both asexual and sexual reproduction. In this context, it typically involves a polyp form (asexual) and a medusa form (sexual).

### Step 2: Analyze each option
- **(a) Hydra**: Hydra primarily reproduces asexually through budding and does not exhibit a medusa stage. Therefore, it does not show metagenesis.

- **(b) Adamsia**: Adamsia, a type of sea anemone, primarily reproduces sexually and does not have a clear alternation between asexual and sexual forms. Thus, it does not exhibit metagenesis.

- **(c) Aurelia**: Aurelia, commonly known as the moon jellyfish, does exhibit a life cycle that includes both a polyp stage (asexual) and a medusa stage (sexual). However, it is not the best example of metagenesis compared to Obelia.

- **(d) Obelia**: Obelia is a colonial organism that exhibits both asexual reproduction (through polyps) and sexual reproduction (through medusa). This clear alternation between the two forms makes Obelia the best example of metagenesis among the options provided.

### Step 3: Conclusion
After analyzing all the options, the organism that exhibits metagenesis is **(d) Obelia**.

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