This is an incomplete question, here is a complete question.
Which is a source of AC current?
A) a battery B) a generator C) chemical cells wired in series D) chemical cells wired in parallel
Answer : The correct option is, (B) a generator
Explanation :
As we know that there are two type of current.
Direct current (DC)
Alternating current (AC)
Direct current : In this, the electric current or charge flows in one direction only.
For example : battery, flashlight, remote control and cell phone are used to operate on direct current.
Alternating current : In this, the electric current or charge changes in periodical direction.
It is used to supply power to houses, office building, etc.
Generators is used to convert mechanical energy into electrical energy and produce alternating current.
Batteries or chemical cells are used to convert chemical energy into electrical energy by a chemical reaction and produce direct current.
From the given options, a generator device is most likely used to operate on alternating current.
While the other options, a battery, chemical cells wired in series, chemical cells wired in parallel is used which is a source of direct current.
Hence, the correct option is, (B) a generator