The correct option is A Iron
The spokes were made from Iron. The term originally referred to portions of a log that had been split lengthwise into four or six sections. The radial members of a wagon wheel were made by carving a spoke (from a log) into their finished shape. A spokeshave is a tool originally developed for this purpose. Eventually, the term spoke was more commonly applied to the finished product of the wheelwright's work, than to the materials he used. The spoked wheel was invented to allow the construction of lighter and swifter vehicles. The earliest known examples are in the context of the Sintashta culture, dating to ca. 2000 BC. Soon after this, horse cultures of the Caucasus region used horse-drawn spoked-wheel war chariots for the greater part of three centuries.