Birds use a variety of cues to navigate during long migrations. Magnetic- field sensing, sun-position tracking, and even olfactory mapping have all been documented across different species. Researchers increasingly suspect that most migratory birds use several of these systems simultaneously, integrating their outputs to compensate when any one cue becomes unreliable.
Which choice best describes the function of the second sentence in the text?
- Acheck_circle
It supports the variety claim by enumerating documented sensing modalities.
- B
It contradicts the variety claim made in the first sentence.
- C
It introduces a new species of bird.
- D
It defines the term 'migration'.
Explanation
The second sentence enumerates examples that support the opening "variety" claim. B is correct.