The correct answer is B because it preserves the forensic evidence from the instance in the correct order. The first step is to take a memory snapshot of the instance and store it in an S3 bucket, as memory data is volatile and can be lost when the instance is stopped. The second step is to stop the instance, which will prevent any further changes to the EBS volume. The third step is to take an EBS volume snapshot of the instance and store it in an S3 bucket, which will capture the disk state of the instance. The last two steps are to detach the instance from the Auto Scaling group and deregister it from the ALB, which will isolate the instance from the rest of the application.

The other options are incorrect because they do not preserve the forensic evidence in the correct order. Option A takes the EBS volume snapshot before the memory snapshot, which can result in inconsistent data. Option C detaches and deregisters the instance before taking any snapshots, which can affect the availability of the application. Option D stops the instance before taking the memory snapshot, which can cause the loss of memory data.