Relaxin hormone is secreted by corpus luteum/corpus albicans.

Explanation

**Step-by-Step Solution:**

1. **Understanding Relaxin Hormone:**
- Relaxin is a hormone that plays a crucial role in the female reproductive system, particularly during pregnancy and childbirth.

2. **Function of Relaxin:**
- The primary function of relaxin is to relax the ligaments in the pelvis and to soften and widen the cervix. This is essential for facilitating childbirth, allowing the baby to pass through the birth canal more easily.

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