The correct answer is D. simile.
Let's go through all of these options together.
A) metaphor is incorrect because the comparison is expressed using the word 'as' which metaphors do not use to compare
B) personification is also incorrect because it is a figure of speech that gives human qualities to non-human entities, such as animals, nature, objects, etc. which is not the case here
C) is the correct answer here. A simile is a figure of speech that compares two or more things using words such as 'like' or 'as,' which is obviously the case here - her face lit up with pleasure as quickly as a light flashing on
