Which set is similar?

Options

A. `"Corpus luteum - Graafian follicle"`
B. `"Sebum - Sweat"`
C. `"Bundle of His -Pacemaker"`
D. `Vit-B_(7)" -Niacin"`

Explanation

To determine which set is similar, we need to analyze the given terms: Corpus luteum, Graafian follicle, sebum, sweat, bundle of His (pacemaker), and vitamin B7 (niacin).

### Step-by-Step Solution:

1. **Identify the Terms**:
- **Corpus luteum**: A hormone-secreting structure that develops in an ovary after an ovum has been discharged.
- **Graafian follicle**: A mature ovarian follicle that is ready to release an egg during ovulation.
- **Sebum**: An oily substance secreted by sebaceous glands in the skin.
- **Sweat**: A fluid produced by sweat glands to help regulate body temperature.
- **Bundle of His**: A collection of heart muscle cells that transmit electrical impulses, acting as a pacemaker.
- **Vitamin B7 (niacin)**: A vitamin that is part of the B-vitamin complex; however, niacin is actually Vitamin B3, not B7.

2. **Group Similar Terms**:
- **Corpus luteum and Graafian follicle**: Both are related to the ovarian cycle and are involved in the process of ovulation and hormone production.
- **Sebum and sweat**: Both are secretions from glands in the skin but serve different functions.
- **Bundle of His**: This is related to the heart's electrical system and does not fit with the other terms.
- **Vitamin B7 (niacin)**: This is a vitamin and does not relate to the other terms in the context of reproductive or glandular functions.

3. **Determine the Most Similar Set**:
- The most similar set is **Corpus luteum and Graafian follicle** because they are both structures involved in the female reproductive system and are part of the ovarian cycle.

### Final Answer:
The similar set is **Corpus luteum and Graafian follicle**.

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