Final answer:
The tonic chord of A major is A major, consisting of the notes A, C⁴, and E. The mnemonic 'Every good boy does fine' is unrelated to tonic chords but helps piano learners remember the notes E, G, B, D, and F on the treble clef.
Step-by-step explanation:
The tonic chord of a key is the chord that represents the starting note of the scale from which the key is named. In the case of A major, the tonic chord is A major. It consists of the notes A, C⁴ (C-sharp), and E, with A being the root note of the chord. When you are learning how to play the piano, phrases like "Every good boy does fine" are mnemonic devices to help remember the order of notes on the lines of the treble clef, which for reference are E, G, B, D, and F. The question presented only offers one correct option for the tonic of A major, which is A major and not A minor, E minor, or E major. Therefore, the correct answer is A major.