In Visual Basic, when are you required to use the keyword End If to close a conditional statement, and when is it not needed?

Introduction / Context:
Visual Basic supports both single line and multi line If statements. Understanding when to use the End If keyword is important for writing syntactically correct conditional logic. This question tests whether you know the difference between a compact, single line If statement and a structured multi line If...Then...Else block, and when End If is required to mark the end of the block.

Given Data / Assumptions:

• We are writing conditional logic using If in VB 6 or VB.NET style syntax.
• Single line statements may look like If condition Then statement.
• Multi line blocks may include If, Then, ElseIf, Else, and End If.
• The compiler needs clear markers to know where a block ends.
• End If is specifically associated with multi line If blocks.

Concept / Approach:
Visual Basic allows a simple single line If statement such as If x > 0 Then y = 1. In this case, the condition and the action are written on one line, and no End If is required, because the end of the line also marks the end of the conditional block. For more complex logic with multiple statements or else branches, you must write a multi line If block: If condition Then ... statements ... Else ... statements ... End If. In this structure, the End If keyword explicitly terminates the block so that the compiler knows where the conditional region ends and subsequent code begins. Omitting End If in a multi line block will result in a syntax error.

Step-by-Step Solution:
Step 1: Identify whether the If statement is single line or multi line. A single line If has the condition, Then, and the action on the same line, with no following Else on separate lines. Step 2: Recognize that single line If statements do not require an End If because they consist of a single statement controlled by the condition. Step 3: For any multi line If...Then block that spans multiple lines, especially when including multiple statements or Else or ElseIf branches, the block must end with an End If keyword. Step 4: Write the full structure as If condition Then, followed by one or more statements, optionally ElseIf and Else blocks on separate lines, and finally End If to close the block. Step 5: Understand that other constructs such as For...Next and Do...Loop have their own terminating keywords and do not use End If.

Verification / Alternative check:
If you try compiling code such as If x > 0 Then y = 1, the compiler accepts it without End If. However, if you write If x > 0 Then, followed by multiple lines of code and no End If, you will see a syntax error indicating that End If is expected. For a For loop, the correct terminator is Next, not End If. This behavior demonstrates that End If is specifically for multi line If blocks and not for single line statements or other control structures.

Why Other Options Are Wrong:
Option B is incorrect because End If is not used after every line of code; it is used only to close multi line If blocks. Option C is wrong because the compiler does not automatically insert End If; you must write it explicitly in multi line cases. Option D misrepresents End If as only appearing in comments, which is false; it is a real language keyword. Option E confuses the syntax for For loops, which end with Next, not End If.

Common Pitfalls:
A common pitfall is accidentally converting a single line If into a multi line structure by adding additional statements on separate lines without adding End If, which causes compilation errors. Another is misaligning Else or ElseIf keywords with the corresponding End If, making code harder to read. Using proper indentation and always pairing If with End If in multi line blocks helps maintain clarity and avoid logical errors.

Final Answer:
In summary, you must use End If to terminate any multi line If...Then or If...Then...Else conditional block, but you do not need End If for single line If statements where the condition and the action appear on the same line.