A number of sentences are given below which, when properly sequenced, form a coherent paragraph, Each sentence is labelled with a letter. Choose the most logical order of sentences from among the four given choices to construct a coherent paragraph.
A. Their growing costs and a growing economy-must be reckoned with realistically.
B. Central programmes persist and in some cases grow.
C. As demand expands, programmes expand.
D. It is extremely difficult to curtail them.