Increasing welding current and decreasing welding speed is the correct answer to increase penetration in welding.

Explanation:

1. Introduction to Penetration in Welding:
Penetration refers to the depth to which the weld material has fused with the base material. It is an important parameter in welding as it directly affects the strength and integrity of the weld joint.

2. Factors Affecting Penetration:
There are several factors that influence the penetration in welding. These include welding current, welding speed, electrode diameter, arc length, and angle of electrode. Among these factors, welding current and welding speed have the most significant impact on penetration.

3. Impact of Welding Current on Penetration:
- Welding current is the measure of the electrical energy supplied to the welding arc. It determines the heat input and the intensity of the arc.
- Increasing the welding current increases the heat input and the temperature of the arc.
- This increased heat input results in higher melting rates and deeper penetration into the base material.
- Therefore, increasing the welding current increases the penetration.

4. Impact of Welding Speed on Penetration:
- Welding speed is the rate at which the welding process is carried out, typically measured in inches per minute.
- Decreasing the welding speed means that the welding process is carried out at a slower rate.
- Slower welding speed allows more time for the heat to be transferred to the base material, resulting in better fusion and deeper penetration.
- Therefore, decreasing the welding speed increases the penetration.

5. Combined Effect of Welding Current and Welding Speed:
- The combination of increasing welding current and decreasing welding speed has a synergistic effect on penetration.
- Increasing the welding current provides more heat input, while decreasing the welding speed allows more time for the heat to be transferred to the base material.
- This combination results in higher melting rates, increased fusion, and deeper penetration.
- Therefore, increasing welding current and decreasing welding speed together maximize the penetration in welding.

In conclusion, to increase penetration in welding, the welding current should be increased, and the welding speed should be decreased. This combination provides higher heat input and more time for heat transfer, resulting in deeper penetration and a stronger weld joint.