C#.NET indexers — A Student class exposes an indexed property over an int[5]. Which usages are correct?

Introduction / Context:
Indexers in C#.NET let an object behave like an array using the syntax obj[index]. They are instance members; C# does not support static indexers. This problem asks which example statements correctly use such an indexed property of a Student class that maps to a 5-element integer array.

Given Data / Assumptions:

• Student defines an instance indexer taking one int parameter.
• We want valid C# syntax and semantics.
• Console.WriteLine can read from the indexer if a get accessor exists.

Concept / Approach:
Valid usage requires a Student instance (constructed with new) and then either assignment via the set accessor or reading via the get accessor. Static-like forms such as Student[3] are invalid. Also, constructs like Student.this are not C# syntax and should be rejected.

Step-by-Step Solution:

Verification / Alternative check:
Declare public int this[int i] { get; set; } inside Student, then compile and test statements 2 and 3 successfully.

Why Other Options Are Wrong:

• 1 and 4: Attempt static indexer access → illegal in C#.
• 5: Nonsensical C# syntax.

Common Pitfalls:
Forgetting that indexers are instance-based; also mixing up property indexers with arrays declared at the type level.

Final Answer:
2, 3