Embryonic stem cells are derived from which of the following?

Embryonic stem cells are specifically derived from human embryos that are typically created through in vitro fertilization processes. During this process, embryos are formed and allowed to develop to a certain stage, where a cluster of cells called the blastocyst is formed. It is from this stage that embryonic stem cells are harvested. These stem cells are pluripotent, meaning they have the potential to differentiate into virtually any cell type in the human body, which is a key reason for their significant interest in research and potential therapeutic applications.

The other options represent different sources of stem cells that do not yield embryonic stem cells. Adult tissues may contain adult stem cells, but they lack the same pluripotency as embryonic stem cells. Bone marrow is another source of stem cells, primarily yielding hematopoietic (blood-forming) stem cells rather than embryonic stem cells. Dermal layers can contain skin stem cells, but again, these are not embryonic stem cells and serve different functions in tissue repair and regeneration. Thus, the most accurate source for embryonic stem cells is indeed human embryos from in vitro fertilization.