Answer:
Correct answer is option B) Core convection helps generate a magnetic field, and the magnetic field creates the magnetosphere.
Explanation:
In its first millions of years, Mars had, just as Earth does today, a cast iron core responsible for generating the magnetosphere, the magnetic shield that repels solar particles. This shield prevents the solar wind from impacting our atmosphere fulfilled the same function on Mars during its first 500 million years.
But Mars is smaller than Earth and, about 4.2 billion years ago, this molten core froze. Upon freezing, the magnetic field was lost and the solar wind swept through the planet's atmosphere.