Which of the following is the best response given that the lower limit of a confidence interval of the difference between the means of two populations is -2.6 and the upper limit is -1.3.

1. We are confident the first population's mean is equal to the second population's mean.

2. We are confident the first population's mean is at least 1.3 less than the second population's mean.

3. none of these

4. We do not have sufficient evidence to conclude the means for the two populations differ.

5. We are confident the second population's mean is at least 2.6 more than the first population's mean.