A LINE DRAWING is the name often given to a graph in which the vertices are not shown (the edges just connect directly) and the edges are all line segments.
For all practical purposes, you can just think of a line drawing as a graph whose vertices are so small that you can't see them.
A line drawing has a UNICURSAL TRACING if it can be traced without lifting
the pencil or retracing any line.
A unicursal tracing is CLOSED if the tracing starts and ends at the same point.
A unicursal tracing is OPEN if the tracing starts and ends at different points.
Based on your knowledge of Euler's Theorems, you should be able to quickly answer the following questions.