**Core Concept**
Steroids are a class of chemical compounds characterized by a specific molecular structure that consists of a steroid nucleus, which is a four-ring system. Steroids can be further classified into different types based on the functional groups attached to the steroid nucleus, such as estrogens, progestins, androgens, and corticosteroids.

**Why the Correct Answer is Right**
Corticosteroids, such as prednisolone, are a type of steroid that are used as anti-inflammatory and immunosuppressive agents in medicine. They work by binding to glucocorticoid receptors in cells, which then translocate to the nucleus and regulate gene expression. This leads to a decrease in the production of pro-inflammatory cytokines and an increase in the production of anti-inflammatory cytokines.

**Why Each Wrong Option is Incorrect**
**Option A:** Estrogens, such as estradiol, are a type of steroid hormone that are involved in the regulation of female reproductive functions. However, estrogens are not typically classified as corticosteroids.
**Option B:** Progestins, such as progesterone, are a type of steroid hormone that are involved in the regulation of female reproductive functions and pregnancy. However, progestins are not typically classified as corticosteroids.
**Option C:** Androgens, such as testosterone, are a type of steroid hormone that are involved in the regulation of male reproductive functions. However, androgens are not typically classified as corticosteroids.

**Clinical Pearl / High-Yield Fact**
It's worth noting that while corticosteroids are not the same as other types of steroids, they can have significant side effects, such as osteoporosis and glaucoma, due to their long-term use.

**Correct Answer:** D