Your answer to your question is D ;)
Conquistadors were soldiers or explorers from the either the Spanish or Portuguese Empire that came in search for land & power, gold, and labor.
One of the causes of the Black death was the involvment of traders and merchants coming from sea and bringing the disease with them. It soread easily due to poor hygiene at the time and not so great medical practices. It killed around 50% of Europes population and and had around a 99-100% fatality rate. It originated in China, but again, it was brought to europe by traders.
The great famine was caused by a disease that destroyed the potato crop which happened to be one of the more available foods at the time. About a million died in result of this and people began to leave Ireland immigrating to places such as the us, australia, britain or canada.
The year 1915 is when Australia voting became mandatory
They could get to know each other without supervision.
and
They had a cheap fast mode of transportation to go to places and to get to school, home and work without the expense of a car.