The reason is #2(sort of)
Going in pairs, as we all know, is practiced by all JW's so that when we are talking to a householder, they don't have time to figure out the gobbledygook that one witness uses before the other one hits them with another bit of "Truth". Elders use the same tactic on their visits so a publisher never has a chance to see which way the conversation is going, thereby becoming so confused, that before they know it,the elders have them tap dancing like crazy.
CIAO4NIAO!!!
alfie