Final answer:
Preschoolers are most likely to fear separation anxiety, as well as other common fears such as monsters and the dark.
Step-by-step explanation:
The most common fear among preschoolers is separation anxiety.
Separation anxiety is the fear or distress that a child experiences when they are separated from their primary caregiver. This fear typically peaks between the ages of 1 and 2, but can also be present in preschoolers.
Preschoolers may also fear other things such as monsters, the dark, or imaginary creatures. These fears are common and often temporary as children develop and grow.