During cell division the process that causes failure of separation of sister chromatids is called

The correct option is C Non-disjunction

• Nondisjunction is the failure of paired chromosomes or sister chromatids attached at the centromere to separate during cell division.
• This results in both the parent chromosomes going into a particular daughter cell while the other daughter cell is devoid of the parent chromosomes.
• Nondisjunction causes errors in chromosome number and results in aneuploidy.
• For example, trisomy 21 (Down syndrome) and monosomy X (Turner syndrome).
• It is also a common cause of early spontaneous abortions.

Thus, the correct answer is option C.