Answer
a) Please see the image. Not all parts of each chromosome are labelled for simplicity, and the image is slightly simplified from the one in the textbook to give more room for labels.
b) A haploid set (there are 4 in the image) has 4 chromosomes, which are still chromatids in this image. A diploid set has twice as many chromosomes, with sister chromatids still attached to one another.
c) The stage shown is metaphase I.
Work Step by Step
For a), skim the chapter to see the parts labelled in various figures, and find corresponding parts in the image from the question. For b), review the meaning of "haploid" and "diploid" and identify where a sufficient number of chromatids/chromosomes are found in the image. For c) the fact that the cell is 4n shows that this is meiosis I, and the chromosomes being lined up in the center of the cell shows that this is metaphase.