In the study of the Indus Valley Civilization, which site is generally regarded as the earliest city discovered within present day India?

Introduction / Context:
This question belongs to ancient Indian history and archaeology, focusing on the Indus Valley Civilization, also called the Harappan Civilization. The earliest major site to be excavated, which led to the recognition of this civilisation, holds special importance. Exams often ask which city was first discovered, because that discovery changed the understanding of Indias ancient urban past.

Given Data / Assumptions:
- The question is about the earliest city discovered in the context of the Indus Valley Civilization.
- It provides several urban sites associated with the Harappan world.
- We assume the question refers to the first major site excavated in the early twentieth century that revealed the existence of this urban civilisation.
- The term earliest here refers to discovery and recognition, not necessarily the oldest phase of occupation in absolute time.

Concept / Approach:
Harappa, located in present day Pakistan, was the first major site of this civilisation to be excavated in the 1920s by archaeologists like Daya Ram Sahni. Its discovery led to the recognition of a previously unknown Bronze Age urban culture in the northwestern part of the subcontinent. Mohenjodaro was excavated soon after and is also extremely important, but Harappa holds the distinction of being the first city that brought this civilisation to light. The approach is to recall the sequence of archaeological discoveries rather than just the relative importance of sites.

Step-by-Step Solution:
Step 1: Identify that the question is about the Indus Valley or Harappan Civilization. Step 2: Recall that the excavation of Harappa in the early twentieth century first revealed evidence of a large, planned urban settlement. Step 3: Recognise that Mohenjodaro was excavated soon after Harappa and became equally famous, but it was not the first discovery. Step 4: Note that Rangpur, Kalibangan and Lothal are later excavated sites which helped expand understanding of the civilisation but do not hold the distinction of earliest discovery. Step 5: Based on this sequence, select Harappa as the correct answer.

Verification / Alternative check:
A simple verification method is to recall the alternative name of the civilisation itself. It is commonly called the Harappan Civilization, named after Harappa, the first major site to be excavated. Standard history textbooks clearly state that Harappa and Mohenjodaro were the first sites discovered, with Harappa slightly earlier. Later sites like Lothal and Kalibangan expanded the geographical picture. This supports the choice of Harappa as the earliest discovered city.

Why Other Options Are Wrong:
Rangpur: An important Harappan site in Gujarat, but discovered later and not the first major city identified.
Mohenjodaro: A key site of the civilisation but excavated after Harappa, so it is not the earliest discovery.
Kalibangan: A Harappan site in Rajasthan, crucial for understanding early and late phases, but identified later.
Lothal: An important port town of the civilisation, excavated in the mid twentieth century, not the first city discovered.

Common Pitfalls:
The most common error is to choose Mohenjodaro because it is very famous and often illustrated in textbooks. Some students also confuse earliest discovered with oldest in terms of date of occupation. The question is about archaeological discovery order, not exact chronological age. Remembering that the civilisation is alternatively called Harappan helps link the earliest discovery with Harappa and prevents confusion.

Final Answer:
Therefore, the earliest city of the Indus Valley Civilization to be discovered was Harappa.