Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the right order to form a meaningful and coherent paragraph.

A. The most common estimate is about 50 ships and 20 airplanes.
B. The exact number of ships and airplanes that have disappeared in the Bermuda Triangle is not known.
C. It is not known whether disappearances in the Bermuda Triangle have been the result of human error or weather phenomena.
D. The wreckage of many ships and airplanes reported missing in the region has not been recovered.