What lines are useful for tree trunk texture?

Correct answer: Irregular vertical lines

Direct answer: irregular vertical lines are useful for showing the texture of a tree trunk. A tree trunk generally grows upward, and its bark often has uneven cracks, grooves, ridges, and marks that run mainly in a vertical direction. The lines should not all be identical; small changes in length, thickness, spacing, and direction make the surface appear natural rather than manufactured. Option A is correct because it combines the general upward direction of the trunk with the irregular quality of natural bark. Option B is incorrect because isolated circles do not normally describe the long grooves and uneven surface of bark. Option C is incorrect because colour without lines may add tone, but it does not clearly communicate the linear texture asked about. Option D is incorrect because folding paper is an action on the material, not a drawing method for bark. Memory cue: natural textures are usually irregular; avoid copying a perfectly repeated pattern.