A Blackboard test's Activity Log shows you detailed information about a student's progress through a test, including when which questions were answered (and saved), how long the student lingered on each question, and when the test was submitted.
On the attempt page for the student test in question, click the TEST INFORMATION link at the top.
Click the Access Log button right of the start date and time.
Blackboard's Attempt Log shows you detailed information about a student's progress through an assessment. For Assignment-type assessments, it shows when the item was opened and submitted. For Test-type assessments, it shows the student's progress through the assessment, including when questions were answered (and saved), how long the student lingered on each question, and when the assessment was submitted.
You will find the activity log on the student submissions list for the assessment in question. Locate the student whose activity log you wish to view, click the "..." button right of their name, then choose ATTEMPT LOG.