Answer:
The ancient lava flows seen on the Moon's surface are most likely a result of partial melting of the Moon's mantle caused by a combination of radioactive decay and residual heat left over from the Moon's formation. This process of magma generation is known as "partial melting" or "melting by decompression." As the mantle rocks slowly rise and undergo a reduction in pressure, some of the minerals in the rocks begin to melt and form magma, which then rises to the surface and solidifies to form lava flows.
Step-by-step explanation: