The Egyptians were keen observers of the stars, as befits a desert civilization. They named the major planets and a number of bright stars. They used groupings of stars known as decans to measure time at night. Most Egyptian star names have not been identified with modern ones. However, references to Sirius, the brightest star in the sky, are clear, as are those to the constellation Orion, which they called Sah or Sahu. The rise of Sirius in the east, just before dawn, after not having been visible for seventy days, was the harbinger of the rising of the Nile waters, close to midsummer.”
—Hugh Murdoch,
“The Pyramid that Points to the Stars”

What did the appearance of Sirius in the east after a long absence tell the ancient Egyptians?
a.
The Nile would soon rise.
c.
Orion would soon appear.
b.
The Nile would soon recede.
d.
Historians do not know.