Cathy is designing a welding machine that can be used to weld thin sheets of steel. The machine uses electricity to heat a thin piece of wire. When the wire touches a metal surface, it melts. The melted wire can be used to bond two pieces of steel together.
One problem Cathy has with her machine is that oxygen mixes with the melted wire, causing it to rust quickly. Which of the following is the best way for Cathy to fix this design problem?
A. Shield the wire from oxygen.
B. Remove all oxygen from inside the building.
C. Use a piece of cloth string instead of a piece of wire.
D. Make the steel from wood.