Question

what are sister chromatids? genetically different strands of dna that complement each other tied together at the centromere a pair of chromosomes identical strands of dna coiled up and tied together at the centromere rewatch

Explanation:

To determine the correct definition of sister chromatids, we analyze each option:

1. The first option says "genetically different strands of DNA that complement each other tied together at the centromere" — Sister chromatids are genetically identical (formed by DNA replication), so this is incorrect.
2. The second option "A pair of chromosomes" — Sister chromatids are not a pair of chromosomes (homologous chromosomes are a pair, sister chromatids are copies of a single chromosome), so this is incorrect.
3. The third option "Identical strands of DNA coiled up and tied together at the centromere" — During DNA replication, a chromosome duplicates to form two identical sister chromatids joined at the centromere, so this matches the definition.

Answer:

The correct option is the one with "Identical strands of DNA coiled up and tied together at the centromere" (the third option in the list, though the exact identifier isn't fully clear from the image, but the text is "Identical strands of DNA coiled up and tied together at the centromere").