The Indus Valley Civilisation is described as a protohistoric civilisation because its people were familiar with which important cultural feature, even though modern scholars have not fully deciphered it?

Introduction / Context:
Historians classify ancient societies into pre historic, protohistoric, and historic phases based on the presence and understanding of written records. The Indus Valley Civilisation, also called the Harappan Civilisation, is often labelled protohistoric rather than fully historic. This question asks why that is so, focusing on what the people of this civilisation already knew, even though modern scholars still face challenges in interpreting it fully.

Given Data / Assumptions:

• The civilisation in question is the Indus Valley Civilisation.
• It is called protohistoric, not purely pre historic or historic.
• The options give possible reasons: writing, art, copper, pottery, or use of iron tools.
• We assume a basic understanding of how written records influence historical classification.

Concept / Approach:
A pre historic society has no written records. A historic society has written records that can be read and interpreted. A protohistoric society has evidence of writing or script, but modern scholars have not yet fully deciphered or understood it. The Indus Valley Civilisation left behind numerous seals and inscriptions bearing a script. Because these symbols exist but are not yet fully deciphered, the civilisation is placed in the protohistoric category. Therefore, the relevant feature is writing, not simply art, pottery, or metallurgy, which can be found in purely pre historic cultures as well.

Step-by-Step Solution:
Step 1: Recall the definitions of pre historic, protohistoric, and historic in archaeology and history. Step 2: Remember that the Indus Valley Civilisation produced a script found on seals, tablets, and pottery. Step 3: Note that this script is not yet fully deciphered, which prevents historians from reading the civilisation's own records. Step 4: Recognise that the presence of undeciphered writing is exactly what makes a civilisation protohistoric. Step 5: Choose “Writing” as the correct answer.

Verification / Alternative check:
You can verify this by reading any standard textbook on ancient Indian history. They consistently describe the Harappan Civilisation as protohistoric due to the presence of a script on seals and other objects. These texts also mention that while many signs and inscriptions have been found, a clear bilingual key has not been discovered, making the script undeciphered. As a result, historians cannot treat the civilisation as fully historic even though writing definitely existed.

Why Other Options Are Wrong:
Art: Many pre historic cultures produced sophisticated art, including cave paintings, without having writing, so art alone does not move a culture into protohistory.
Copper metallurgy: Knowledge of copper is important for technology but has nothing to do with the classification of pre historic versus historic.
Pottery making: Pottery is widely found in pre historic times and does not by itself create a protohistoric label.
Use of iron tools: Iron came into widespread use later and is not a defining feature of the Indus Valley Civilisation, which is a Bronze Age culture.

Common Pitfalls:
Some students confuse protohistoric with prehistoric and think that having pottery or metal tools is enough to change the classification. Others may incorrectly choose pottery because they remember many references to Harappan pottery. To avoid this, always link protohistory specifically with the presence of writing that exists but cannot yet be fully read or interpreted.

Final Answer:
The Indus Valley Civilisation is called protohistoric because its people knew writing, even though their script remains undeciphered.