Explanation of the answer:

The correct answer is option 'D', which means the given expression results in a boolean value 'True'.

The given expression is:

, 18 , a) b) c) d)

To understand the expression, we need to know the following concepts:

1. Comma operator: In Python, the comma operator (",") is used to evaluate two or more expressions and return the last one. For example, the expression 1, 2, 3 will evaluate all three expressions but return 3.

2. Boolean expressions: In Python, boolean expressions are used to compare values and return a boolean value (True or False). For example, 5 > 3 will return True because 5 is greater than 3.

Now, let's break down the given expression:

1. The first expression is ", 18". This expression will evaluate to 18 because the comma operator returns the last expression.

2. The second expression is ", a)". This expression will evaluate to 'a)' because the comma operator returns the last expression.

3. The third expression is "b)". This is a string literal, so it will evaluate to 'b)'.

4. The fourth expression is "c)". This is also a string literal, so it will evaluate to 'c)'.

5. The fifth expression is "d)", which is a string literal and will evaluate to 'd)'.

6. Finally, we have all the expressions separated by commas, so the comma operator will evaluate all expressions and return the last one, which is 'd)'.

7. Since 'd)' is a non-empty string, it is considered True in boolean expressions. Therefore, the given expression results in True.

In conclusion, the correct answer is option 'D' because the given expression evaluates to a boolean value True.