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 age (in weeks) at which their child was first able to creep or crawl a distance of four feet within one minute. The researchers also recorded the average outdoor temperature (in F) six months after the baby's birth date. For each month of the year, the researchers selected one baby, at random, born in that month. If we fit the least-squares line to 12 data points (one for each month), we obtain the following results from a software package. (Not that temperature is the explanatory variable and crawling age is the response.) A 90% confidence interval for the slope of the least-squares regression line is (approximately)

0.078 0.041. 0.078 0.046. 0.078 0.056.