Step 1: Understanding the Question:
Five positive numbers A, B, C, D, E obey three chained inequalities, and we must decide, using the two extra clues one at a time, whether we can always tell that A is the largest of the five.
Step 2: Key Formula or Approach:
The trick with chained inequalities like these is to add or compare them in pairs so that common terms cancel, leaving a direct comparison between just two of the letters at a time. We do this systematically, letter pair by letter pair, first using only the stem, then bringing in each statement.
Step 3: Detailed Explanation:
From the stem: $A+B<C+D$ and $C+D<E+A$ share the block $C+D$, so $A+B<E+A$, which gives $B<E$ once A cancels. This is true regardless of any statement.
Now bring in statement 1, $D+E<A+B$. Since the stem gives $A+B<C+D$, stacking these two: $D+E<A+B<C+D$, so $D+E<C+D$, and cancelling D gives $E<C$.
Next, use statement 1 again with the stem's second inequality $B+C<D+E$: stacking $B+C<D+E<A+B$, the second half from statement 1, gives $B+C<A+B$, and cancelling B gives $C<A$.
So far, under statement 1: $E<C<A$, and separately $B<E$, so altogether $B<E<C<A$, meaning B, C and E are each below A.
For D, rearrange statement 1 as $D<A+B-E$. Because $B<E$, the quantity $B-E$ is negative, so $A+B-E$ is strictly less than A. So $D<A+B-E<A$, meaning D is below A too.
With all of B, C, D, E shown to be less than A, statement 1 by itself settles the question with a clear yes, A is the greatest.
Now check statement 2, $E<C$, by itself, without statement 1. Pick sample positive values that satisfy the three stem inequalities plus $E<C$: let $D = 5$, $E = 8$, $C = 12$, and solve for A and B so all three stem conditions hold, for example $B = 0.5$ and $A = 10$. Every stem inequality and $E<C$ checks out with these numbers, yet $C = 12$ exceeds $A = 10$. Since A fails to be the greatest in this valid case, statement 2 by itself cannot guarantee the answer.
Step 4: Final Answer:
Statement 1 by itself is strong enough to force B, C, D and E all below A, so it alone answers the question. Statement 2 by itself allows a counter-example where A is not the greatest, so it alone is not enough. The correct choice is that statement (1) alone is sufficient.
\[ \boxed{\text{Statement (1) alone is sufficient}} \]