Answer:
Human and animal muscle.
Explanation:
I don't mean this literally. If a farmer didn't own an ox to pull his plow, he would have to pull himself. Or with wheels, you would have animals walk in a circle, or crank the wheel yourself.
"<span>c. more than two million years</span>" would be the best option, since this usually means the amount of time between when the first humans appeared on Earth and when they developed a system of writing.
I would say b, but that is a guess
<span><span>Italian
unification (Italian: Unificazione italiana</span><span><span>), or the Risorgimento</span> meaning resurgence
or revival), was the political and social movement that consolidated
different states of the Italian peninsula into the single state of the Kingdom
of Italy in the 19th century. The process began in 1815 with the Congress of
Vienna and was completed in 1871 when Rome became the capital of the Kingdom of
Italy. The memory of the Risorgimento is central to both Italian politics and
Italian historiography, for this short period (1815–60) is one of the most
contested and controversial in modern Italian history. Italian nationalism was
based among intellectuals and political activists, often operating from exile.</span></span>
