At What Age Do Babies Learn to Crawl? Does It

Multiple Choice

At what age do babies learn to crawl? Does it take longer to learn in the winter when babies are often bundled in clothes that restrict their movement? Data were collected from parents who brought their babies into the University of Denver Infant Study Center to participate in one of a number of experiments between 1988 and 1991.Parents reported the birth month and the age at which their child was first able to creep or crawl a distance of 4 feet within 1 minute.The resulting data were grouped by month of birth: January,May,and September. The data are to be analyzed with the Kruskal-Wallis test.The null hypothesis is that the crawling ages have the same distribution in all groups.What is the alternative hypothesis?

A) Not all three mean crawling ages are equal.
B) The mean crawling age in September is higher than the other 2 months.
C) The crawling times in September are systematically higher than in the other 2 months.
D) None of the above.