An intrinsic silicon sample has 1 million free electrons at room temperature. As the temperature is increased

Answer: Option C

In an intrinsic semiconductor like silicon,
the number of free electrons is equal to the number of holes.
This is because electrons are freed when a covalent bond is broken,
creating both a free electron and a hole (a missing electron in the bond).

As the temperature increases,
more covalent bonds are broken due to increased thermal energy.
This generates more electron-hole pairs.
For every broken bond, one electron and one hole are created.

Therefore, the number of free electrons and holes increases,
and they increase by the same amount because they are generated in pairs.

So, the correct answer is Option C.