Final answer:
The correct word to describe the children's reaction to the lion's roar is 'startled' suggesting a sudden surprise or fright.
Step-by-step explanation:
The context of your question suggests that we are looking for a word that describes the reaction of the children to the lion's roar. The appropriate word to fill in the blank is 'startled'. This means that the children were surprised or frightened suddenly by the noise but not to the extent of being terrified, which implies extreme fear. while 'fascinated' and 'intrigued' can indicate a strong interest or curiosity they do not correctly describe a startled reaction. Thus, the sentence should read: 'A few of the children were startled by the lion's roar, but most of them were not frightened.'