<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A randomized controlled trial is conducted investigating the effects of different diagnostic imaging modalities on breast cancer mortality. 8,000 women are randomized to receive either conventional mammography or conventional mammography with breast MRI. The primary outcome is survival from the time of breast cancer diagnosis. The conventional mammography group has a median survival after diagnosis of 17.0 years. The MRI plus conventional mammography group has a median survival of 19.5 years. If this difference is statistically significant, which form of bias may be affecting the results?? A: Selection bias, B: Misclassification bias, C: Lead-time bias, D: Recall bias, E: Because this study is a randomized controlled trial, it is free of bias,  <response>: This is a randomized controlled trial comparing two diagnostic imaging modalities for breast cancer - conventional mammography alone vs conventional mammography plus MRI. The outcome is survival time from breast cancer diagnosis. The MRI plus mammography group has longer median survival than mammography alone group. The question asks what type of bias may be affecting the results, if the difference is statistically significant.This appears to be an example of lead-time bias. Lead-time bias occurs when one diagnostic test detects cancer earlier than another, but does not actually prolong survival. So the time from diagnosis to death is longer, but time from onset of cancer to death is unchanged. Here, adding MRI appears to prolong survival after diagnosis, but it may just be detecting cancers earlier without affecting the course of the disease.This is not selection bias, because patients were randomized. It is not misclassification bias, because there is no error in classifying the outcome. It is not recall bias, as this deals with differences in patient reporting based on memory. And it is not free of bias, because lead-time bias may be present.C: Lead-time bias 