Answer:
Step-by-step explanation:
To find the least element of the dual poset of (A, <), we need to find the element that is greater than or equal to every other element in the dual poset.
A dual poset is obtained by reversing the order relation of the original poset. So, if we reverse the order relation < to >, we will get the dual poset.
Given the Hasse diagram, we see that there is no element that is greater than or equal to every other element in the dual poset. Therefore, the least element of the dual poset does not exist, which corresponds to option a. None.
