Understand the relationship between power, voltage, current, and losses.

The power ($P$) transmitted is given by the formula $P = V \cdot I$, where $V$ is voltage and $I$ is current. The power loss ($P_{loss}$) in transmission lines due to resistance ($R$) is given by $P_{loss} = I^2 R$.

For a constant amount of power $P$ to be transmitted, if the voltage $V$ is increased, the current $I$ must decrease ($I = \frac{P}{V}$).

Since power loss is proportional to the square of the current ($I^2$), a significant reduction in current $I$ (due to high voltage) leads to a much larger reduction in $I^2 R$ losses. This makes high voltage transmission more efficient for long distances.

Option B correctly states that high voltage minimizes $I^2 R$ losses by reducing the current.

The final answer is $\boxed{\text{B. It minimizes } I^2 R \text{ losses by reducing the current}}$

Arc welding involves high electrical currents. If this current passes through sensitive components like antifriction bearings, it can cause localized heating, arcing, and pitting on the bearing surfaces. This damage can lead to premature failure of the bearing.

To prevent damage, the welding current must be directed only through the work piece and back to the welding machine, avoiding any unintended paths through precision mechanical components.

Option C directly addresses this concern by stating that one should avoid allowing welding current to pass through the bearing. Options A and B are either incorrect or would increase the risk of damage.

The final answer is $\boxed{\text{C. Avoid allowing welding current to pass through the bearing}}$