The correct answer for this question is option 'A' - the magnitude of gate voltage and gate current for triggering an SCR is inversely proportional to the temperature.

Explanation:
To understand why the gate voltage and gate current for triggering an SCR are inversely proportional to temperature, let's break down the working principle of an SCR.

1. What is an SCR?
- An SCR (Silicon Controlled Rectifier) is a three-terminal semiconductor device that acts as a switch, allowing current flow in one direction only.
- It consists of three layers of semiconductor material (P-N-P-N) with a gate terminal for control.
- The anode is connected to the P-layer, the cathode is connected to the N-layer, and the gate is connected to the P-layer near the cathode.

2. Triggering an SCR:
- The SCR can be triggered into conduction (ON state) by applying a positive voltage pulse to the gate terminal with respect to the cathode.
- This gate voltage should be sufficiently high to overcome the forward voltage drop across the PN junctions and the voltage required to break down the junctions.

3. Temperature effect on gate voltage and gate current:
- The forward voltage drop across the PN junctions, known as the forward voltage (VF), decreases with an increase in temperature. This is due to the decrease in the barrier potential at the junctions.
- As the temperature increases, the gate voltage required to trigger the SCR decreases because it needs to overcome a smaller VF.
- Therefore, the magnitude of gate voltage for triggering an SCR is inversely proportional to the temperature.

4. Gate current requirement:
- The gate current required to trigger an SCR is directly proportional to the temperature.
- At higher temperatures, the carriers become more mobile, leading to an increase in the conductivity of the device.
- This increased conductivity requires a higher gate current to maintain the same level of control over the SCR.
- Therefore, the magnitude of gate current for triggering an SCR is inversely proportional to the temperature.

Conclusion:
In summary, the magnitude of gate voltage for triggering an SCR is inversely proportional to the temperature because the forward voltage drop across the PN junctions decreases with temperature. On the other hand, the magnitude of gate current for triggering an SCR is directly proportional to the temperature because the increased conductivity at higher temperatures requires a higher gate current for control.