A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to

Options

A. poor selection of modulation index (selected `0ltmlt1`)
B. poor bandwidth selection of amplifiers
C. poor selection of carrier frequency
D. loss of energy in transmission.

Explanation

To solve the question regarding why a male voice sounds like that of a female after modulation and transmission, we can follow these steps:

### Step 1: Understand the Modulation Process
Modulation is the process of varying a carrier signal in order to transmit information. In this case, the information is the audio signal of a male voice.

**Hint:** Recall that modulation involves changing the properties of a carrier wave (like amplitude, frequency, or phase) to encode the information.

### Step 2: Analyze the Options
We have four options to consider:
1. Poor selection of modulation index
2. Poor bandwidth selection of amplifiers
3. Poor selection of carrier frequency
4. Loss of energy in transmission

**Hint:** Think about how each option could affect the quality and characteristics of the transmitted signal.

### Step 3: Identify the Key Issue
The problem states that the male voice sounds like a female voice after transmission. This suggests that the frequency characteristics of the voice have changed, likely resulting in a higher frequency.

**Hint:** Consider how the frequency of the modulated signal can be altered during transmission.

### Step 4: Relate Frequency to Bandwidth
In amplitude modulation (AM), the bandwidth of the modulated signal is determined by the frequency of the modulating signal. The bandwidth is typically twice the frequency of the modulating signal. If the bandwidth is not properly selected, it can lead to distortion in the received signal.

**Hint:** Remember that the frequency of a male voice is generally lower than that of a female voice.

### Step 5: Conclude the Correct Option
Given that the frequency of the received modulated signal becomes higher, the most likely cause is poor bandwidth selection of amplifiers. This can lead to the distortion of the original signal, making a male voice sound like a female voice.

**Hint:** Focus on how bandwidth selection directly impacts the fidelity of the transmitted audio signal.

### Final Answer
The correct option is **Option 2: Poor bandwidth selection of amplifiers**.