The question below comprises four scattered segments of a paragraph. Identify from among the four choices the sequences that correctly assemble the segments and complete the paragraph.

A. As a result, the world has undergone a transformation.

B. Science and civilization have made rapid strides especially in recent times.

C. This constitutes the basic factor in the use of productive resources.

D. But behind all the progress of mankind is the human factor which is invaluable and irreplaceable.