What is always contained in the core of every virus particle?

Every virus particle, or virion, contains either DNA or RNA in its core, which is essential for the virus's ability to replicate and take over host cells. This genetic material is surrounded by a protein coat called the capsid, and, in some viruses, there may be an additional lipid envelope. The presence of DNA or RNA is critical because it carries the information necessary for producing new virus particles once the virus infects a host cell.

The other options do not consistently apply to all viruses. While proteins are present in the form of capsid proteins that shield the genetic material, they are not the core component. Carbohydrates and lipids may be present in certain virus structures but are not universally found in the core of every virus. Thus, the genetic material—either DNA or RNA—remains the defining element that is always found in the core of every virus particle.