Thomas and Chess labeled babies who took a long time to adjust to new experiences, tended to react negatively and intensely to stimuli and events, and were irregular in their eating and sleeping habits as: a. slow to warm up.
b. easy.
c. difficult.
d. quick to calm down.

c. difficult.

Explanation:

Thomas and Chess are researchers who cataloged babies' temperaments based on the ease and speed with which they adapt to the universe around them, in addition, this categorization is associated with adjusting babies to their biological specificities. Within this categorization, babies referred to as "difficult" are those who do not have regular biological characteristics such as eating and sleeping. In addition, these babies have difficulty getting used to and accepting bad situations, showing negative mood and irritable behaviors.

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