Maximal and minimal elements of a partial order

On the set A = {a, b, c}, where a, b, c are pairwise distinct, consider the relation R = {(a,a), (b,b), (c,c), (a,c)}.

List all the maximal and minimal elements of this partial order.

How would I answer this question? I know that the answer is:
Maximal elements = b, c
Minimal elements = a, b

But I don't know why. What makes those maximal and minimal elements?

Thanks.

Aside from the reflexive relations, all you know is that a≤c so a is not maximal. That leaves b and c.

Similarly, you know that c is not minimal and that leaves a and b.