The . . . . . . . . words of the mother comforted the . . . . . . . . child.

The mother’s words were soothing because they were kind and comforting. They helped the child to feel better when they were feeling disappointed.

The other options are incorrect because they do not accurately describe the mother’s words.

• Harsh words are not kind or comforting. They can make someone feel worse.
• Sweet words can be kind and comforting, but they are not necessarily soothing.
• Soft words can be kind and comforting, but they are not necessarily soothing.
• Melodious words can be pleasant to hear, but they are not necessarily soothing.
• Playful words can be fun and entertaining, but they are not necessarily soothing.

In conclusion, the correct answer is E. soothing, disappointed.