As far as I understood, you should have attached this pic.
In this case, here are the answers
1) I can see there two major triads, so the answer is obviously A and B.
2) When the chord is not capabable for using and does not sound properly broken we use word Arpeggio, so the answer is B
3) A triad is the fifth note chord, which is a set of three notes. B
4) The top note of the triad is called the fifth, according to the basic rules, so the answer is C
5) The interval between the root and the third of a major triad is made up of four half steps which makes it sound smooth and holistically.
6) In a major key, major triads can be built on all above scale degrees as it is the most flexible point.
I do hope you will find it useful! Regards.