A 2-year-old girl is brought to the office due to concerns about her development. The girl says approximately 40 words and does not string words together. She can jump, walk upstairs slowly, build a 6-block tower, and follow short commands. She feeds and helps to dress herself. The girl's mother says, "My daughter is such a happy child. She loves playing with the other kids at day care. She is affectionate and caring toward us and her dog. I don't know why she won't speak. Her sister was using sentences by age 2. Is there something wrong with her?" Which of the following is the most appropriate response by the physician?
1) Every child is different; we will reevaluate her development next year.
2) Her speech delay raises concern for autism spectrum disorder and requires further evaluation.
3) I am concerned that your child may have global developmental delay.
4) There is no need to worry; your child's development is within the normal range.
5) This is most likely selective mutism and can be easily treated.
6) Your child may have a language disorder and could benefit from further assessment.