Which of the following is a matrix with one column?

A matrix with one column is known as a column matrix. This type of matrix is characterized by having multiple rows but only one column, which allows it to represent vectors in a vertical orientation. Column matrices are an essential concept in linear algebra and have various applications in business and social sciences, such as representing systems of equations or transformations.

In contrast, a square matrix has the same number of rows and columns, making it a different structure than a column matrix. The identity matrix, which is a specific type of square matrix, contains ones along its main diagonal and zeros elsewhere, again differing from the single-column format. A row matrix has one row and multiple columns, which also distinguishes it from a column matrix. Thus, the correct identification of a matrix with one column is indeed a column matrix, reinforcing the importance of recognizing various matrix types and their configurations.