Step 1: Identify the longest river.
The Nile River in Africa is traditionally recognized as the longest river in the world, with a length of approximately 6,650 kilometers, though the Amazon is a close contender.
Step 2: Match with the options.
Option (B) correctly identifies the Nile.
Step 3: Eliminate distractors.
(A) Amazon - Slightly shorter or comparable, depending on measurement.
(C) Yangtze - Third longest.
(D) Mississippi - Shorter.
(E) Congo - Shorter.
Therefore: The correct answer is (B). \[
\boxed{\text{B}}
\]