In which of the following transformers, the `beta`-particles are emitted?
a. Proton ot neutron b. Neutron to proton
c. Proton to proton d. Neutron to neutron

Options

A. a. Proton ot neutron
B. b. Neutron to proton
C. c. Proton to proton
D. d. Neutron to neutron

Explanation

To determine in which of the given transformations beta particles are emitted, we need to analyze each option carefully.

### Step 1: Understand Beta Particle Emission
Beta particles are high-energy, high-speed electrons (beta minus, β-) or positrons (beta plus, β+). In nuclear reactions, beta minus decay occurs when a neutron is transformed into a proton, emitting a beta particle (electron) and an antineutrino.

### Step 2: Analyze Each Option
1. **Proton to Neutron**: This transformation would involve the emission of a positron (beta plus decay), not a beta minus particle. So, this option does not emit beta particles.

2. **Neutron to Proton**: This transformation involves the conversion of a neutron into a proton, which emits a beta particle (electron) and an antineutrino. This is the correct transformation that emits beta particles.

3. **Proton to Proton**: This transformation does not involve the change of a proton into another proton; thus, no beta particles are emitted. Typically, this would involve gamma emission if any energy change occurs.

4. **Neutron to Neutron**: Similar to the proton to proton case, this transformation does not involve a change of a neutron into another neutron, and thus, no beta particles are emitted. This would also typically involve gamma emission if energy is released.

### Conclusion
The only transformation that emits beta particles is the **neutron to proton** transformation.

### Final Answer
**b. Neutron to proton**

---