Rachel wants her graph to emphasize the relation of each city’s precipitation to each other city’s at each point in time. What kind of graph would be appropriate?

b.  line graph

Explanation:

Line Graphs are very useful in a number of fields ranging from Business, to Sciences to Statistics and others because of it's usefulness in presenting data in charts.

Line graphs are often most suitable and used for representing data over time/ course of a period  so that a relationship can be easily spotted. As such, it can be very useful to Rachel as she aims to show precipitation levels in the different cities.

This is down to the fact that even though there are different cities, the line graph can be plotted in such a way that it will have different lines representing different cities and thus encapsulate the data such that the relationships between each city’s precipitation to each other city’s at each point in time is very visible and emphasized.

the rebels’ chances of victory at lexington & concord were fairly slim, given the fact that most of them very untrained and they were up against the world's greatest military force.  

b) to encourage free trade