Consider the following statements about concrete sleepers. 1. They improve the track modulus. 2. They have good scrap value. 3. They render transportation easy. 4. They maintain the gauge quite satisfactorily. Of these statements

• A. 1 and 2 are correct
• B. 2 and 3 are correct
• C. 3 and 4 are correct
• D. 1 and 4 are correct