What Evidence Is There That Mars May Have Had an Internal

Multiple Choice

What evidence is there that Mars may have had an internal magnetic dynamo in its youth?

A) Phobos and Deimos, the two moons of Mars, show residual radioactivity, as if they had orbited through the high-energy charged particles of a former Martian magnetosphere.
B) There is no evidence that Mars has ever had an internal magnetic dynamo.
C) "Fossilized" regions of opposite magnetic polarity have been found near Mars's north and south geographic poles.
D) Magnetic fields at the surface of Mars show interlocking patterns similar to those produced on Earth by magnetic reversals in Earth's internal dynamo.