For each of the following questions, arrange the sentences A, B, C, and D between sentences 1 and 6 to form a logical sequence with sentence 1 and sentence 6 as the starting sentence and the concluding sentence respectively.
(1) Once upon a time, a rat lived on the bank of a river.
A- A dog, who lived near the bank, saw the rat.
B- Spotting a chance to save a life, he jumped into the water.
C- One day, it accidentally fell into the water.
D- He saw that all the efforts of the rat to stay afloat were failing.
(6) The rat was thus rescued.