A key uncertainty for the next pandemic is what the microorganism responsible might be. In recent history, in nearly all pandemics the causative agent has been a virus — with influenza A being the most common pandemic-causing virus.

This question asks, at high level, which type of microorganism might be responsible for the next pandemic. In this question, the options are:

Orthomyxoviridae virus family (includes influenza A)

Coronaviridae virus family (any coronavirus, excluding SARS-CoV-2)

A virus from one of the other 24 known human-infecting virus families (see the fine print of this question)

A microorganism that is not from one of the 26 known human-infecting virus families.

In the subquestions, "HIVF" stands for "human-infecting virus family."