Sentence given in each question, when properly sequenced, from a coherent paragraph. The first and last sentences are 1 and 6, and the four in between are labelled A, B, C and D. Choose the most logical order of these four sentences for among the four given choices to construct a coherent paragraph from sentences 1 to 6.

1) Commercially reared chicken can be unusually aggressive, and are often kept in darkened sheds to prevent them pecking at each other.

A. The birds spent far more of their time—up to a third — pecking at the inanimate objects in the pens, in contrast to birds in other pens which spend a lot of time attacking others.

B. In low light conditions, they behave less belligerently, but are more prone to ophthalmic disorders and respiratory problem.

C. In an experiment, aggressive head-pecking was all but eliminated among birds in the enriched environment

D. Altering the birds’ environment, by adding bales of wood-shavings to their pens, can work wonders.

6) Bales could diminish aggressiveness and reduce injuries; they might even improve productivity, since a happy chicken is a productive chicken.