Concept:
The Western Himalayan region has unique climatic, geographical, and socio-economic characteristics due to mountainous terrain and harsh environmental conditions.
Step 1: Statement (A)
• Summers are mild due to high altitude.
• Winters are extremely cold with snowfall.
Thus, this statement is correct.
Step 2: Statement (B)
• Major perennial rivers like Ganga, Yamuna originate here.
• These rivers flow throughout the year.
Thus, this statement is correct.
Step 3: Statement (C)
• Terrain is mountainous and difficult.
• Population is sparse and mostly rural.
• Urban development is limited.
Thus, this statement is incorrect.
Step 4: Statement (D)
• The climate is suitable for temperate fruits.
• Apples are grown in large quantities.
Thus, this statement is correct.
Final Conclusion:
\[
\boxed{\text{Option (C) is incorrect}}
\]