Baby elizabeth has a low activity level, is somewhat negative, and displays a low intensity of mood. she would best be described as

slow-to-warm-up.

Explanation:

Baby Elizabeth has the temperament described as slow-to-warm-up. These babies have difficulties relating to others, are very shy and do not get used to new experiences. These babies tend to reject and ignore any new people or things, exhibit low moods, handle life cautiously, a little negatively, usually observe everything around them, and are not very active children. These babies end up being overrated and when this occurs they tend to move away.