Concept:
WGS84 (World Geodetic System 1984) is a global geodetic reference system used for mapping, navigation, and satellite positioning.
It defines a standard reference datum and reference ellipsoid for the Earth.
Step 1: Understand WGS84.
WGS84 provides
• Reference ellipsoid
• Geodetic coordinate system
• Earth-centered coordinate framework
• Standard datum used by GPS
Step 2: Identify its classification.
Hence,
\[
\boxed{\text{WGS84 is a Geodetic Datum}.}
\]
Therefore, the correct option is
\[
\boxed{(B)\;\text{Datum}.}
\]