While tuning in a certain broad cast station with a receiver, we are actually

Options

A. varying the local oscillator frequency
B. varying the frequency of the radio signal to be picked up
C. tuning the antenna
D. none of these

Answer

To solve the question, we need to understand what happens when we tune a receiver to a broadcast station.

1. **Understanding the Receiver Tuning Process**: When we tune a radio receiver to a specific broadcast station, we are essentially adjusting the receiver to pick up the frequency of the radio signal being transmitted by that station.

2. **Identifying the Options**:
- Option A: "Wearing the local oscillator frequency" - This is not correct as we are not adjusting the local oscillator directly.
- Option B: "Wearing the frequency of the radio signal to be picked up" - This option seems plausible but is not the most accurate description of what we are doing.
- Option C: "Tuning the antenna" - This is the most accurate description, as the antenna needs to be tuned to resonate at the frequency of the incoming signal.
- Option D: "None of this" - This option is incorrect since we are indeed tuning something.

3. **Conclusion**: The correct answer is option C: "tuning the antenna". When tuning in a broadcast station, we are effectively adjusting the antenna to match the frequency of the radio signal being transmitted.

### Step-by-Step Solution:
1. **Identify the process of tuning a radio receiver**: Understand that tuning involves adjusting the receiver to pick up a specific frequency.
2. **Analyze the given options**: Evaluate each option to see which one accurately describes the tuning process.
3. **Determine the correct answer**: Conclude that tuning the antenna is the primary action taken when tuning into a broadcast station.