A because you have to go up in thirds
True, as technology got better and better, these music groups around the world were able to cater to a larger audience. Since a trend is something seen, copied, and then repeated, this is therefore a technological trend. (this is just from off the top of my head so I may be wrong.)
27.9 cm by 22.4 cm or 11.0 in by 8.8 in
