What will happen if a cuboid's depth is shown too little?

Correct answer: It may look like a flat rectangle

A cuboid is recognized as a three-dimensional form through the visible relationship among its length, width, and depth. If the depth is drawn too small, the side plane becomes extremely narrow and contributes very little to the impression of volume. The front face then dominates the image, so the object may be read as a flat rectangle rather than a solid cuboid. Option A is correct. It does not become round, because reducing depth does not create curved surfaces, and it does not become a pyramid, because its basic geometric structure has not changed into a pointed form. Option D is also incorrect: realism depends on believable proportions, perspective, and light, not simply on reducing one dimension. The artist should compare all three dimensions and use consistent receding edges.