The correct answer to this open question is the following.
Although the question is incomplete because it does not provide a specific reference about the author of the letter or any other reference, we can comment on the following.
A primary source is the piece of information that was written by a character or an individual that lived in the moment of the event, was part of the event, or witnessed the event. This individual could have written a letter, or a document -including a book. Or he/she took a photograph. Or was part of an interview. The secondary source includes information from a third person who was not part of the time or event but has found information through other resources. It is the case of an encyclopedia or researchers/historian books.
Answer: B ) The arms race
Explanation: The nuclear arms race was an arms race competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War. During this very period, in addition to the American and Soviet nuclear stockpiles, other countries developed nuclear weapons, though none engaged in warhead production on nearly the same scale as the two superpowers.
They fought with the americans becaues the revolutionary war was to end slavery so they blacks helped them fight the war so they could be free and no longer slaves.
<span>Advancements in navigation. The Gupta Empire were very advanced in the fields of technology, science and art. The scholar Aryabhatta calculated that a solar </span>year was 365.358, <span>he also calculated </span>pi<span> to the fourth decimal place at a </span>value of 3.1416. <span>Kings in the </span>Gupta empire<span> owned huge copper, gold, and iron mines, and made advancements in metalworking. </span>
