Answer:
B. centromere
Step-by-step explanation:
Identical chromatids are attached to each other at the centromere.
Other incorrect answers:
A. centriole
The centriole is an organelle that produces the mitotic spindle, also called spindle fibres.
C. spindle
Also called mitotic spindle or spindle fibres, they are produced by the centrioles. The spindle is like long, thin tentacles that attach to the centromeres and move the chromosomes within the cell. During metaphase, they move chromosomes to the equator or metaphase plate. During anaphase, they pull chromosomes apart.
D. chromosome
Chromosomes are condensed DNA. It is the entire structure which includes a centromere. The number of chromosomes in a cell is counted by the number of centromeres.