It’s a trick question.  The answer is always those that are relevant, material and cannot be obtained elsewhere.  In the Fourth Department, this case states the rule:Riordan v Cellino & Barnes, P.C.
2011 NY Slip Op 03769 ;Decided on May 6, 2011 ; Appellate Division, Fourth Department
 

"Memorandum: Plaintiffs commenced this legal malpractice action seeking damages allegedly resulting from the negligence of defendants in their representation of Clarence F. Riordan (plaintiff) in the underlying Labor Law and common-law negligence action. Plaintiff commenced the underlying action seeking damages for injuries that he sustained when he was working on the reconstruction of a school building in East Rochester. Defendants, however, failed to serve a timely notice of claim against East Rochester Schools (see Matter of Riordan v East Rochester Schools, 291 AD2d 922, lv denied 98 NY2d 603), and a jury returned a verdict of no cause of action with respect to plaintiff’s claims against the remaining defendant in the underlying action. Defendants admit that they were negligent in failing to serve the notice of claim in a timely manner, but they contend that they are not liable for legal malpractice on the ground that the underlying action against East Rochester Schools has no merit. "