In the first century AD, Greek engineer Heron of Alexandria ______

In the first century AD, Greek engineer Heron of Alexandria ______ the first wind wheel to operate a machine.
a) invented
b) had invented
c) has invented
d) was inventing

Верный ответ a) invented, так как в предложении известно точное время, когда было совершено деянье (In the first century AD), следственно, нужно употребить глагол в форме Past Simple: In the first century AD, Greek engineer Heron of Alexandria invented the first wind wheel to operate a machine.