Answer:
Experts are critical of caregivers using bouncy seats or swings for prolonged periods of time.
Step-by-step explanation:
The correct word to be placed in the blank space is prolonged. The idea given by the statement is that experts do not subscribe to or endorse the use of bouncy seats or swings for children for a long amount of time.
Even though exercise is needed by children for their growth, the prolonged use of bouncy seats and swings could result in dizziness and this might be dangerous to the health of the children. Prolonged in this case means, long or lengthy.