C#.NET — Using an instance property with get and set: which statements compile and run? Assume class Sample defines a non-static property Length with both get and set accessors. Which of the following statements are valid?

Introduction / Context:
The problem tests whether you can distinguish between instance versus static property access and evaluate valid reads/writes when a property has both get and set accessors.

Given Data / Assumptions:

• Length is an instance property of Sample with get and set.
• Statements:
• 1) Sample.Length = 20;
• 2) Sample m = new Sample(); m.Length = 10;
• 3) Console.WriteLine(Sample.Length);
• 4) Sample m = new Sample(); int len; len = m.Length;
• 5) Sample m = new Sample(); m.Length = m.Length + 20;

Concept / Approach:
Non-static properties must be accessed through an instance. Reads require get; writes require set. Using the type name for a non-static property does not compile.

Step-by-Step Solution:

Verification / Alternative check:
Marking Length as static would change 1 and 3, but the question specifies an instance property, so the provided evaluation stands.

Why Other Options Are Wrong:
Any option including 1 or 3 is invalid because they rely on static access.

Common Pitfalls:
Confusing static and instance members; assuming properties behave differently than fields with respect to static access.

Final Answer:
2, 4, 5