This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to measure a straight line distance using a topo map
Lay a piece of paper down on the map and mark it.
Place a straight edge of a piece of paper onto your map. Line up the edge with both the first (" point a ") and second (" point b ") points you want to measure the distance between, then make a tick mark on the paper where each point is.

Pick from:
1). Make sure your piece of paper is long enough to make your 2 tick marks. Note that this method works better for shorter line distances.;
2). For example, identify where you want the line to start. Mark the point of the line to be measured by tracing a centimeter or two horizontally on either side of that edge.;
3). Point a is expressed in triangle forms to mark the distance between the first point and second point. Point b is expressed in squared forms to mark this distance between two points.;
4). Read the most important line in your diagram. You will use the help that your map needs to be able to accurately determine the distance between two adjacent bodies of water.;
The answer is:
1).