Step 1: Write down what is given.
We are told A, B, C, D, E are all positive, and:
\[ A + B < C + D \quad (i) \]
\[ B + C < D + E \quad (ii) \]
\[ C + D < E + A \quad (iii) \]
We want to know if A is bigger than every one of B, C, D, E.
Step 2: Get one fact for free, before using either statement.
Chain (i) and (iii) together: \( A + B < C + D \) and \( C + D < E + A \), so \( A + B < E + A \).
Cancel A from both sides: \( B < E \). This holds no matter what, straight from the question stem, with no statement needed yet.
Step 3: Test statement 1 alone: \( D + E < A + B \).
Combine this with (i): \( D + E < A + B < C + D \), so \( D + E < C + D \). Cancel D: \( E < C \).
Combine statement 1 with (ii): \( B + C < D + E \) and \( D + E < A + B \) from statement 1, so \( B + C < A + B \). Cancel B: \( C < A \).
We now know \( E < C < A \), so \( E < A \) as well.
From Step 2, \( B < E \), and we just showed \( E < A \), so \( B < E < A \), giving \( B < A \).
For D: statement 1 says \( D + E < A + B \), so \( D < A + B - E \). Since \( B < E \), the quantity \( B - E \) is negative, so \( A + B - E \) is less than A. Combining, \( D < A + B - E < A \), so \( D < A \).
We have now shown all four: \( B < A \), \( C < A \), \( D < A \), \( E < A \). So statement 1 alone is enough to conclude A is the greatest.
Step 4: Test statement 2 alone: \( E < C \).
Try to build a valid, positive-number example using only the original three inequalities plus \( E < C \), and see whether A always comes out biggest.
Take \( A = 10 \), \( C = 12 \), \( D = 5 \), \( E = 8 \), \( B = 0.5 \). Check: \( A + B = 10.5 \), \( C + D = 17 \), so (i) holds. \( B + C = 12.5 \), \( D + E = 13 \), so (ii) holds. \( C + D = 17 \), \( E + A = 18 \), so (iii) holds. Also \( E < C \), since \( 8 < 12 \), so statement 2 holds.
But here \( C = 12 \) is bigger than \( A = 10 \), so A is NOT the greatest in this valid example. This shows statement 2 alone can be true while A is not the biggest number, so statement 2 alone cannot conclusively answer the question.
Step 5: Decide between the answer choices.
Statement 1 alone is enough to prove A is the greatest, in every case satisfying it. Statement 2 alone is not enough, since a valid counter-example exists where A is not the greatest. So exactly one of the two statements, statement 1, works by itself.
Final Answer:
Statement 1 alone answers the question; statement 2 alone does not.
\[ \boxed{\text{Statement (1) alone is sufficient}} \]