Question

identify the hole symbol below:
diameter
counterbore
countersink
depth

Explanation:

In engineering drawings, the symbol shown (a downward arrow with a horizontal line at the top) is the standard symbol for indicating the depth of a hole. Diameter is usually denoted by the Greek letter phi ($\phi$), a counterbore has a specific symbol with a larger - diameter section representation, and a countersink has a conical - like symbol.

Answer:

Depth