The correct answer is option 4, which states that the structure at Banawali yielded many beads in finished, semi-finished, and unfinished states.

Option 1 is true, as Harappan beads were indeed made of various materials such as gold, copper, shell, lapis lazuli, ivory, and semi-precious stones. This diverse range of materials suggests the craftsmanship and skill of Harappan bead-makers.

Option 2 is also true, as archaeologists have identified bead-makers` shops based on collections of unfinished objects. This indicates that bead-making was an important craft in the Harappan civilization, with specialized workshops dedicated to it.

Option 3 is true as well, as at the site of Chanhudaro, tools, furnaces, and beads in various stages of preparation have been found. This provides further evidence of the existence and practice of bead-making during the mature Harappan period.

Therefore, the correct answer is option 4. However, it is important to note that the other options are true and highlight significant aspects of bead-making in the mature Harappan civilization.