Question

what happens during anaphase? chromosomes line up in the middle of the cell; chromatin condenses and coils to form chromosomes; spindle fibers form at the centrosomes; centromeres split and chromatids separate

Explanation:

Anaphase is a stage of mitosis/meiosis where the centromeres holding sister chromatids together split, and the separated chromatids (now chromosomes) are pulled to opposite poles by spindle fibers. The other options describe events from earlier stages: chromosomes lining up is metaphase, chromatin condensing is prophase, and spindle fiber formation is late prophase/prometaphase.

Answer:

Centromeres split and chromatids separate