Concept:
Bench terracing is a soil and water conservation practice used on sloping lands.
Step 1: Check runoff reduction.
Bench terraces reduce overland flow and runoff velocity.
\[
A \text{ is correct}
\]
Step 2: Check soil erosion control.
By reducing slope length and runoff speed, bench terracing minimizes soil erosion.
\[
B \text{ is correct}
\]
Step 3: Check moisture conservation.
Terraces retain more water and improve soil moisture storage.
\[
C \text{ is correct}
\]
Step 4: Check land use.
Bench terracing helps convert steep land into cultivable land and supports permanent agricultural practices.
\[
D \text{ is correct}
\]
Step 5: Check pollution statement.
Keeping the environment pollution free is not a direct objective of bench terracing in this context.
\[
E \text{ is not selected}
\]
Thus:
\[
A,B,C,D
\]
\[
\therefore \text{Correct Answer is (B)}
\]