Which of the following search methods is used in the investigation of a large open outdoor scene such as an air crash disaster site?

In the strip (line) method searchers walk abreast in parallel lanes across the area; it is the method suited to large open outdoor scenes such as air crash debris fields. Spiral and wheel methods radiate from or towards a centre and suit smaller scenes; the zone method divides a defined area (e.g. a building or vehicle) into sectors.