Who is welcomed into Vallhalla? chosen warriors
Nobody can enter Vallhalla
only those who could not cross the rainbow bridge
all Northmen

the correct answer is a. how to make proposal that works.

indeed, the register is quite formal and the tone is especially objective as it avoids the use of the first and second person singular (i, you) and opts instead for the third person plural which is more impersonal and focuses on the data and the argument that is being developed by the author. the formality adds the impression of respectability to the work and the impersonality adds objectivity to it.