Read the following statements carefully
`Y`: The resistivity of semiconductor decreases with increases of temperature.
`Z`: In a conducing solid, the rate of collisions between free electrons and ions increases with the increase of temperature.
Select the correct statement (`s`) from the following
a. `Y` is true but Z is false b.`Y` is false but `Z` is true
c.Both `Y` and `Z` are true d. `Y` is true `Z` and `Z` is the correct reason for `Y`

Explanation

To solve the question, we need to analyze the two statements provided:

**Statement Y**: The resistivity of a semiconductor decreases with an increase in temperature.
**Statement Z**: In a conducting solid, the rate of collisions between free electrons and ions increases with an increase in temperature.

### Step 1: Analyze Statement Y
- **Explanation**: In semiconductors, as the temperature increases, the thermal energy provided to the electrons allows some of them to jump from the valence band to the conduction band. This results in an increase in the number of charge carriers (electrons) available for conduction, thereby increasing the conductivity and decreasing the resistivity.
- **Conclusion**: Statement Y is **true**.
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