The figure shows the timing report for the verilog module Design code.

$1.$Based on this timing report, answer the starting and ending points of the critical path $(2\%)$ and draw this critical path on the circuit diagram of $($a$)(3\%).$

$2.$According to the timing report, what problem occurred in this circuit? If a problem occurred, explain the cause and describe how to modify the circuit to solve this problem $(5\%).$