In what month of the calendar do most of the previous events occur?

January

Explanation:

In the month of January, most of previous events happened such as addition of  Ireland to Great Britain, signed the Declaration of the United Nations by more than twenty countries, Queen Victoria was announced herself the empress of India, diplomatic relations were established between China and the U.S., Alaska was added as the 49th state of U.S, Czech and Slovak republics are formed and 11 European countries began using a new single European currency which is Euro.

ford’s revolution of the assembly like to make cars less expensive

explanation:

porter is writing economic history because he is focusing on the cost of developing vaccines.