Explanation:

Among the sites listed, Mohenjodaro has not yielded evidence of a pre-Harappan settlement.  It is considered a major urban center of the Mature Harappan phase, dating approximately from 2600 BCE to 1900 BCE.  Excavations at Mohenjodaro have not revealed earlier cultural layers predating this mature phase.

In contrast:

Harappa: This site exhibits multiple occupational layers, including evidence of an Early Harappan (pre-Harappan) phase, indicating settlement before the Mature Harappan period.  

Kalibangan: Located in present-day Rajasthan, Kalibangan has revealed both Early Harappan and Mature Harappan phases. Notably, it features the world's earliest known ploughed field, dating to the pre-Harappan period.  

Dholavira: Situated in Gujarat, Dholavira shows evidence of occupation from the Early Harappan through the Mature Harappan phases. Recent studies suggest that its earliest layers date back to around 3500 BCE, indicating a pre-Harappan settlement.  

Therefore, among the options provided, Mohenjodaro is the site where a pre-Harappan settlement has not been found.