In guitar music, especially electric guitar, a power chord    (also fifth chord) is a colloquial name for a chord that consists of the root note and the fifth. Power chords are commonly played on amplified guitars, especially on electric guitar with distortion. Power chords are a key element of many styles of rock and especially in heavy metal, and punk rock.

Can we draw the following conclusion?
a power chord can be called the fifth cord


1). Yes.
2). It's impossible to say.
3). No.
1).