**Core Concept**
Newer progestational contraceptives primarily act by inhibiting ovulation through a mechanism that involves the hypothalamic-pituitary-gonadal axis. These contraceptives disrupt the normal feedback inhibition of gonadotropin-releasing hormone (GnRH) secretion, leading to a decrease in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion.

**Why the Correct Answer is Right**
The newer progestational contraceptives, such as levonorgestrel and desogestrel, act by binding to the progesterone receptor in the hypothalamus, which leads to an increase in the expression of kisspeptin. Kisspeptin is a potent stimulator of GnRH secretion. However, the increase in GnRH secretion is not sufficient to overcome the negative feedback inhibition caused by the progestin, resulting in a decrease in LH and FSH secretion. This decrease in LH and FSH secretion prevents ovulation, thereby providing effective contraception.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the primary mechanism of action of newer progestational contraceptives. While some older progestational contraceptives may have primarily acted by thickening the cervical mucus, this is not the primary mechanism of newer progestational contraceptives.

**Option B:** This option is incorrect because it does not accurately describe the primary mechanism of action of newer progestational contraceptives. While some contraceptives may have primarily acted by thinning the uterine lining, this is not the primary mechanism of newer progestational contraceptives.

**Option D:** This option is incorrect because it does not accurately describe the primary mechanism of action of newer progestational contraceptives. While some contraceptives may have primarily acted by causing an increase in the risk of thrombosis, this is not the primary mechanism of newer progestational contraceptives.

**Clinical Pearl / High-Yield Fact**
It is essential to note that while newer progestational contraceptives are effective in preventing ovulation, they may still have side effects such as irregular bleeding and mood changes. Additionally, these contraceptives may not provide complete protection against sexually transmitted infections.

**Correct Answer: C**