I think its <span>dark and dim. </span>
I personally think B is correct because it overall sums up what is being suggested in the paragraph
Knots usually take 1 minute or so to do. If you keep on tying the knots and get used to the pattern, you will get faster and faster and eventually will be able to do it in 4 seconds. It is kind of like picking strawberries. If you keep on picking strawberries and timing yourself, you will get faster like when you typed the knot