Porque means "because" in Spanish (and Portuguese).
Answer:
1. Introduction of electronic mail (e-mail)
2. Bulky and slow post service delivery
Explanation:
In the past decade, paper mail was the major means of communication as a sender could write his mail, out his address and that of the receiver and send it through the Post Office.
However, there came a peak from 2006 after there was a record of over two hundred billion pieces and it began to decline until then to about one hundred and fifty billion pieces in the Fiscal Year 2014.
Some of the factors that have contributed to the decline in mail volume has been the better, and more efficient means of electronic mail, which rendered paper mail redundant
C.friction heat would make it not slide because the road would be not wet magnetism has nothing to do with it and gravity same so the most probably answer is c.friction (sorry if I don't make sense)
