Which of the following statements is incorrect?

a- Most Harappan settlements have a small high western part and a larger lower eastern section.
b- At Dholavira and Lothal the entire settlement was fortified and sections within the lower towns were separated by walls.

Both statements are correct.

Most Harappan settlements have a small high western part and a larger lower eastern section. At Dholavira and Lothal the entire settlement was fortified and sections within the lower towns were separated by walls. The Citadel within Lothal was not walled off, but was built at a height.