Will mark brainliest! (77 pts) only if an answer is right. no trolling, will be reported!

what makes mitochondrial dna useful as a molecular clock?

a. it is only found in select organisms, making it easier to compare relationships between species that have it.
b. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations.
c. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other.
d. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species.

i'm leaning towards b, because it says the exact same sentence in the lesson, only it says survival or function instead of structure or function.

i think a and d are completely wrong.