The correct answer is option 4: "It refers to the people of Meluhha". This statement is not correct because the Harappan script does not refer to the people of Meluhha.

Option 1 states that the Harappan script has about four hundred signs. This is true as archaeologists have discovered a large number of unique symbols, often referred to as signs, in the Harappan script.

Option 2 states that the Harappan script was written from right to left. This is true as the majority of the inscriptions found in the Harappan script are written in a right-to-left direction, similar to other ancient scripts like Sumerian and Egyptian.

Option 3 states that the Harappan script has been found on bone rods and jewelry. This is also true as archaeological excavations have revealed inscriptions in the Harappan script on various objects such as seals, tablets, pottery, and even personal ornaments like beads and amulets.

To summarize, the Harappan script consists of about four hundred signs, was written from right to left, and has been found on various objects. However, it does not specifically refer to the people of Meluhha.