**Core Concept**
The question is testing the student's knowledge of non-steroidal contraceptives, which are hormonal methods of birth control that do not contain steroids. In this context, the correct answer refers to a type of non-steroidal contraceptive that works by altering ovulation, making it difficult for a woman to become pregnant.

**Why the Correct Answer is Right**
The correct answer is likely a type of progestin-only contraceptive, but not a steroid itself. However, since the question asks for a non-steroidal contraceptive, it's more likely referring to a non-hormonal method that mimics the effects of steroids. One such method is the copper intrauterine device (IUD), which releases ions that alter the uterine environment, making it inhospitable for fertilization. The copper IUD is an effective non-steroidal contraceptive that works by altering ovulation and fertilization.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, so we cannot comment on its accuracy.
**Option B:** This option is also not specified, so we cannot comment on its accuracy.
**Option C:** This option is likely a steroid-based contraceptive, such as oral contraceptives or injectable contraceptives, which contain hormones like estrogen and progesterone. These are steroid-based, not non-steroidal.
**Option D:** This option is also likely a steroid-based contraceptive, similar to Option C.

**Clinical Pearl / High-Yield Fact**
Copper IUDs are a highly effective non-steroidal contraceptive method, with a failure rate of less than 1%. They are also reversible and do not affect hormone levels, making them a popular choice for women who want a non-hormonal method of birth control.

**Correct Answer: C. Copper intrauterine device (IUD)**