Objective: How to cut a new center plank for your picnic table?

Which of the following solutions is more sound in terms of naive physics reasoning?

Choose from: (a). With the trough dimension measured on the center plank we can chop off the ends. Using a chisel the ends were cleanly cut from the center plank. The ends pieces were then reattached to the table on the new end cleats.. (b). With the trough dimension measured on the center plank we can chop off the ends. Using a saw the ends were cleanly cut from the center plank. The ends pieces were then reattached to the table on the new end cleats..
(b).