Which of these would have the greatest potential energy?
a) a roller coaster at the top of a hill.
b) a roller coaster half-way up the hill.
c) a roller coaster half-way down the hill.
d) a roller coaster at the bottom of the hill.

The open systems interconnection (osi) reference model: defines standards for many aspects of computing and communications within a network. is a generic description for how computers use multiple layers of protocol rules to communicate across a network. defines standards for wireless local area network (wlan) communication protocols. details the advantages and disadvantages of various basic network cabling options.