Spike moss is

Options

A. (a) Selaginella
B. (b) Funaria
C. (c) Lycopodium
D. (d) Adiantum

Answer

### Step-by-Step Solution:

1. **Identify the Common Name**: The question asks about "spike moss." Recognizing that spike moss is a common name is the first step.

2. **Scientific Classification**: The scientific name for spike moss is Selaginella. This is crucial for understanding its classification.

3. **Taxonomic Group**: Spike moss (Selaginella) belongs to the group known as Pteridophyta. This is important for categorizing the plant within the plant kingdom.

4. **Appearance**: The term "moss" in spike moss comes from its appearance, which resembles that of true mosses. This helps in understanding why it has this common name.

5. **Vascular System**: Spike moss has a well-defined vascular system, which is a characteristic feature of higher plants, distinguishing it from non-vascular plants like true mosses.

6. **Additional Information**: It is referred to as an "arboreal form," indicating that it can grow in tree-like structures or habitats.

7. **Conclusion**: Based on the above characteristics, we conclude that the correct answer to the question is option A, Selaginella.

### Final Answer:
Spike moss is Selaginella (Option A).

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