Which BEST describes the problem with this sentence?

As a small child, Katrina's grandmother used to visit every Christmas.
A) run on sentence
B) misspelled words
C) dangling modifier
D) sentence fragment

Was the grandmother the small child referred to?

it was c

Or was it Katrina?

no

it was kartina

Then it’s unclear about which person the phrase is referring to, right?

Which of the choices are obviously wrong, now that you know the problem is with that phrase?

yep, its C