The probability of a randomly selected person being a teacher and preferring to use a Mac is
. The correct answer choice is C.

The probability of a randomly selected person being a teacher and preferring to use a Mac can be calculated by dividing the number of teachers who prefer Macs by the total number of people surveyed.
The number of teachers who prefer Macs is 150, and the total number of people surveyed is 500.
So, the probability is:
![\[ \text{Probability} = \frac{\text{Number of teachers who prefer Macs}}{\text{Total number of people surveyed}} \]](https://img.qammunity.org/2024/formulas/mathematics/college/lua609lw3q1dib99zn0jj3b9wrn0ekdjmx.png)
![\[ \text{Probability} = (150)/(500) \]](https://img.qammunity.org/2024/formulas/mathematics/college/g2c2vlmxjt8calqk6phfsya4kp0vua7foe.png)
Simplifying the fraction:
![\[ \text{Probability} = (3)/(10) \]](https://img.qammunity.org/2024/formulas/mathematics/college/v9amceancogc0ko4h4pya90f6ml8k2s4hm.png)
Therefore, the correct answer is:
C.
