Which of the following would reduce the resistance of a metal wire?
increasing its length
increasing its temperature
increasing its thickness
all of the above

increasing its thickness

Explanation:

there are four major factors that affect the resistance of a metal wire, they are;

1. the length of the wire: the longer the length of a wire the higher the resistance

recall R=ρL/A

the above equation shows a direct relation between resistance and length

2. the temperature of the wire: the higher the temperature of a wire when heated up, the higher the resistance of the wire

3. the thickness or width of the wire: the higher the thickness the lower the resistance.

from the equation in 1 above, there is an inverse relationship between resistance and area(diameter inclusive) of a wire

4. the material of the wire: different wires have different values of resistivity(ρ). steel  shows higher levels of resistivity than copper

therefore, increasing thickness reduces resistance

photocells convert light energy to electricity

temp rises, and expansion