TOPIC: Mock Exam Question on Story Maps

This question has 2 answers that I think are correct and don't understand why one is more correct than the other.

Story maps can be used to:
A. Functionally decompose a system
B. Slice functionality into chunks that can be delivered iteratively
C. Provide a project road map
D. Drive a retrospective technique that focuses on milestones, checking points, and other time-ordered events in an iteration

The answer sheet states it's B. However, isn't C correct too and if so why is B more correct?

Thanks.

I read this question without reading the answer and chose the correct answer using a process of elimination.
I reached the correct answer, but I can't be sure if the author of this question had the same thought process.
I got down to either B or C, and then eliminated C because I felt like a road map is generally discussed as features to be released where as a story map decomposes features into related user stories that can be delivered at different times.
I feel like B is always true, where C is only sometimes true.
You could potentially develop a product increment for feature 2 before you finish all the product increments needed to complete feature 1.
The story map is at a more detailed level than a road map and doesn't necessarily roll up exactly to the road map.

I believe 'C' is incorrect, because it says "Provide a project road map".. but Story Map is a product features/Story mapping per Releases following the priorities.