Identify the True Statement(s) of the Different Types of Holes

Multiple Choice

Identify the true statement(s) of the different types of holes in closest packed structures.
1. Trigonal holes are formed by three spheres in the same layer.
2. Tetrahedral holes are formed when a sphere sits in the dimple of four spheres in an adjacent layer.
3. Octahedral holes are formed between two sets of three spheres in adjoining layers of the closest packed structures.

A) ​1 only
B) ​2 only
C) ​​3 only
D) ​1 and 3
E) ​1 and 2