One of the following is not the causal organism for ringworm.

Options

A. Microsporum
B. Trichophyton
C. Epidermophyton
D. Macrosporum

Answer

To determine which of the following options is not a causal organism for ringworm, we will analyze each option provided:

1. **Microsporum**: This is a genus of fungi that is known to cause ringworm infections. It is one of the primary causal organisms for tinea corporis (ringworm).

2. **Trichophyton**: This is another genus of fungi that is also responsible for causing ringworm. It is commonly associated with various dermatophyte infections, including tinea corporis.

3. **Epidermophyton**: This genus is also known to cause ringworm infections. It is involved in dermatophyte infections of the skin.

4. **Macrosporum**: This option is not a recognized genus associated with ringworm. The correct genus is Microsporum, and Macrosporum does not cause ringworm infections.

Based on this analysis, the option that is not a causal organism for ringworm is **Macrosporum**.

### Final Answer:
**Macrosporum** is not the causal organism for ringworm.

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