Answer:
The personality dimension conscientiousness best describes Melissa. 
Step-by-step explanation:
The Big Five Personality Traits, there are 5 core traits and they can be high or low on an individual: 
- Openness
 - Conscientiousness
 - Agreeableness
 - Neuroticism 
 - Extraversion
 
In this case, Melissa's personality dimension can be understood as conscientiousness since this trait is known for being a thoughtful person as well as controlled, primarily with impulses. This person tends to be organized and mindful of his/her behavior and how it can affect others. 
Melissa is described as dependable and as a reliable individual, main qualities of the conscientiousness personality dimension.