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