Question

In a series circuit with three bulbs,
a. there are many paths for the current to take.
b. the remaining two bulbs are not affected if one bulb burns out.
c. all of the bulbs become dimmer as more bulbs are added.
d. a switch is never used.

Answer 1

In a series circuit, there is only one path for current to take. 
If more bulbs are added, then the same current loses more energy,
making heat and light on its way through more bulbs, so the ones that
were there before become dimmer.