Explanation:

The question asks for the attribute that defines the distance between two adjacent cells, typically in a tabular or grid layout context (e.g., HTML tables). Option A, 'Width', refers to the horizontal dimension of an individual cell or element. It does not define the space *between* cells. Option B, 'Height', refers to the vertical dimension of an individual cell or element. It also does not define the space *between* cells. Option C, 'Cell padding', defines the space *between the content of a cell and its border*. It is an internal spacing within a cell, not the space separating cells from each other. Option D, 'Cell spacing', is the attribute that specifies the amount of space, in pixels, between the borders of adjacent cells in a table. This directly corresponds to the 'distance between two adjacent cells' as described in the question. Therefore, 'Cell spacing' is the correct attribute for controlling the separation between table cells.