Sister chromatids during meiosis
It is C. During S-phase the DNA of each chromosome duplicate and the two sister chromatids formed get attached by cohesin proteins. These sister chromatids separate at Anaphase-II of Meiosis.

From wikipedia:


  A sister chromatid refers to either of the two identical copies (chromatids) formed by the replication of a single chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said as 'one-half' of the duplicated chromosome. A full set of sister chromatids is created during the synthesis (S) phase of interphase, when all the chromosomes in a cell are replicated.