Aclosed circle with short lines inside on a topographical map
a)relief
b)depression
c)elevation
d)topographic map
e)contour interval
f)index contour

Option (B)

Explanation:

A topographic map is defined as the map that describes the topography of an area, where the elevations of the areas are highlighted using the contour intervals, the location of different places are marked, hills, basins, and valleys are also easily identified, and also shows the extent of rock in any particular direction. They are comprised of map scale and north direction that enables a geologist or geographer to understand the features of a particular area.

In a topographic map, the depressions or the basins are often designated in the form of a circle comprising of short lines inside it and they have the least elevation, often found on or below the sea level.

Thus, the correct answer is option (B).

it should be p1 v1 = p2 v2

it's c (engineer's do their work with mechanical stuff not on any living being)