Two or more arrays whose elements are related by their position (subscript) in the arrays are called _____ arrays

The correct answer is: C. parallel arrays

A parallel array is a set of two or more arrays whose elements are related by their position (subscript) in the arrays. For example, if we have two parallel arrays, $A$ and $B$, then the element in $A$ at position $i$ is related to the element in $B$ at position $i$.

The other options are incorrect for the following reasons:

• A. horizontal arrays are arrays that are arranged horizontally. This is not a property of parallel arrays.
• B. paired arrays are arrays that are paired together. This is not a property of parallel arrays.
• D. related arrays are arrays that are related in some way. This is a very broad definition, and it could apply to parallel arrays, but it could also apply to many other types of arrays.
• E. vertical arrays are arrays that are arranged vertically. This is not a property of parallel arrays.

In conclusion, the correct answer is: C. parallel arrays.