Which assisted reproduction technique involves fertilization occurring outside of the body?

In-Vitro Fertilisation (IVF) is the assisted reproduction technique in which fertilization occurs outside of the body. During this process, an egg is retrieved from a woman's ovaries and is combined with sperm in a laboratory setting. This allows for the fertilization of the egg to take place outside the natural environment of the female reproductive system. After a few days of development in the lab, one or more embryos can then be transferred back into the woman’s uterus in hopes of achieving a successful pregnancy.

This differentiates IVF from other techniques. For example, artificial insemination involves directly introducing sperm into a woman's reproductive tract without facilitating fertilization in a lab setting. Gamete Intrafallopian Transfer (GIFT) and Intracytoplasmic Sperm Injection (ICSI) also occur inside the body: GIFT involves placing both eggs and sperm into the fallopian tubes, while ICSI injects a single sperm directly into an egg, typically conducted as part of an IVF cycle. Thus, IVF is uniquely characterized by its key step of external fertilization, making it the correct answer.