Parallelogram ABCD is shown. Point E is the midpoint of segment AB. Point F is the midpoint of segment CD. Which transformation carries the parallelogram onto itself?

a reflection across line segment AC

a reflection across line segment EF
a rotation of 180 degrees clockwise about the origin

a rotation of 180 degrees clockwise about the center of the parallelogram

which of the following sets of data would produce the largest value for an independent-measures t statistic? the two sample means are 10 and 20 with variances of 20 and 25 the two sample means are 10 and 20 with variances of 120 and 125 the two sample means are 10 and 12 with sample variances of 20 and 25 the two sample means are 10 and 12 with variances of 120 and 125