The type of details used in this sentence is chronological details - Stone Age happened first, and it was followed by Bronze Age and Iron Age.
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
Choice B which is direct object
