In a ring design WAN:
a. messages can take a long time to travel from the sender to the receiver
b. a message arrives at all computers on the network simultaneously
c. messages always arrive faster than in other types of layouts
d. messages are delivered directly from sender to receiver because there is a point-to-point connection directly between each sender and each receiver
e. messages always take one second to travel between sender and receiver

a. messages can take a long time to travel from the sender to the receiver

Explanation:

In a ring design WAN:  messages can take a long time to travel from the sender to the receiver

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.