Spore formation occurs during ______

Explanation

**Step-by-Step Solution:**

1. **Understanding Spores**: Spores are haploid cells, meaning they contain a single set of chromosomes. They are typically unicellular and can develop into a new organism.

2. **Formation of Spores**: Spores are produced through a process called meiosis, which occurs in a structure known as the sporangium. This sporangium is part of a diploid organism called the sporophyte.

3. **Conditions for Spore Formation**: Spores are formed during unfavorable conditions. When environmental conditions are not suitable for growth and reproduction, the sporophyte undergoes meiosis to produce spores.

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