To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) In all If...Then statements - This option is incorrect. The "End If" statement is not required in all If...Then statements. It is only required in multi-line If...Then statements.
Option B) In all Multi-line statements with Else - This option is correct. In multi-line If...Then statements that include an Else clause, the "End If" statement is required to indicate the end of the If...Then block.
Option C) In Single Line statements - This option is incorrect. In single-line If...Then statements, the "End If" statement is not required.
Option D) Both a and b - This option is incorrect. Option A is incorrect, as mentioned earlier.
Option E) All of the above - This option is incorrect. Option C is incorrect, as mentioned earlier.
Therefore, the correct answer is B) In all Multi-line statements with Else. This option is correct because the "End If" statement is required in multi-line If...Then statements that include an Else clause to indicate the end of the If...Then block.