Answer:
b. question of fact
Explanation:
A policy represents a proposed principle of action by an organization, individual or government.
A fact represents a process or an event that has been proven to be always true.
A theory is a hypothesis that has been proven by several independent individual or researcher.
Global warming means the average increase in global temperature as a result of absorption of more radiation by greenhouse gases. The phenomenon has been established and proven as a fact.
Hence, Ned will be addressing a question of fact rather than a question of policy or theory.
The correct option is b.