What does the # symbol indicate in the following command:$$#yy$?$

Question $37$ options:

a$)$

It represents the number of times to repeat the command automatically.

b$)$

It indicates that the editor should save and close upon command completion.

c$)$

It indicates that the command must be executed starting at the root.

d$)$

It represents the number of lines you want to yank.