Which sentence is correct, i.e., do I need a comma?
I will introduce the topics A, B, and C.
OR
I will introduce the topics, A, B, and C.
Which sentence is correct, i.e., do I need a comma?
I will introduce the topics A, B, and C.
OR
I will introduce the topics, A, B, and C.
Usually when introducing a list after a sequence of words consisting of {verb} + {noun}, a comma and a colon can both be used.
For a comma, the first sentence would be more conventional
I will introduce the topics A, B, and C.
For a colon, it's the same as the second sentence except the first comma is replaced with a colon
I will introduce the topics: A, B, and C.
As one user suggested, the reason why "I will introduce the topics, A, B, and C." is less common is that it could be incorrectly interpreted. One could read it and think that you will be introducing four things as opposed to three topics, with the four things being the topics, A, B, and C. A sentence that could exemplify this is
I will introduce the topics, objectives, proposals, and results.
With this sentence it's hard to tell if "objectives, proposals, and results" are the topics or if they are separate from the topics.
Assuming A B and C are the topics, the first option is better. By inserting the comma one could read it that "topics" is in the list of things being introduced.
To me, the best way to use the commas in this sentence is no comma after topic and no comma after B: 'I will introduce the topics A, B and C.' Example: 'I will introduce the topics strategy design, strategy implementation and strategy evaluation.'
The use of a comma after B may be justified to avoid confusion on the different parts of the enumeration. Example: 'I will introduce the topics strategy design, strategy implementation and de-implementation, and strategy evaluation.'
This is logopaedic interpunction, putting commas before each spoken emphasis. This came up with writing comments in social media, and it is wrong. <-- see my perfectly woven in example of using this type of comma correctly in that sentence?
Regarding your question: Correctly, it should read "...the topics A, B and C. " (simple enumeration)
The use of a comma before and+a last object applies only when you mention another fact that is of importance in the context but logically or semantically different from the ones before. It usually includes a complete sentence like in "I'd like to introduce topics A, B, C and D, and E is of importance, too." but doesn't have to.