How long it took to fix a defect from introduction to completion of the fix is the best and correct answer. Defect cycle time is the measurement of the time it takes to fix a defect once it’s discovered. The length of the defect cycle
time directly affects the cost and time frame of an iteration or cycle time. The other responses are incorrect because it’s not how many defects are discovered, but how long it takes to fix each one; the person who is creating the
defects isn’t part of the defect cycle time; although an estimate’s accuracy of cycle time is tracked, it’s not part of the defect cycle time’s total amount.