Which of the following secretes the hormone, relaxin, during the later phase of pregnancy?

The correct answer is Corpus luteum.

Relaxin is a hormone that plays a key role in the female reproductive system, particularly during pregnancy and childbirth. During the later phase of pregnancy, it is primarily secreted by the corpus luteum, which is a temporary endocrine structure in the ovary.

The functions of relaxin include:
- Relaxing the ligaments in the pelvis and softening the pubic symphysis to widen the birth canal for parturition.
- Dilating and softening the cervix to facilitate childbirth.
- Inhibiting uterine contractions early in pregnancy to maintain pregnancy stability.