A scientist studied four fossils of a marine mammal dating back to 50 million years, 45 million years, 40 million years, and 30 million years ago. Which fossil is most similar to the present-day mammal? 30 million years
40 million years
45 million years
50 million years

The 30 million years ago, because it's the closest one to us, wait is there a picture to it ?

before there were tanks, machine guns, windmills, and solar panels, the first civilizations emerged that create the history of humanity which provided the larger context for western civilization. uses of weaponry and technology were used very differently in the ancient civilizations than they are today. relating back to the times of the ancient mesopotamian civilization, technology kept advancing throughout the ancient egyptian civilization into the ancient greek civilization, and then finally the ancient roman civilization. as techniques and strategies were past down from civilization to civilization, each shared its own similarities, as well as varied differences. one trait they had in common was to commit violence and economically overpower one another. technology has ultimately advanced due to the knowledge transferred from generation to generation. uses of sophisticated weaponry and devices have created more opportunity for warfare and improvement in the work place. ancient civilizations became more powerful due to the advancements of technology. technology did not only create the use of violence, but it also the economies grow and become stronger, because production of trading goods rose like never before. the rivers, such as the nile, tigris, and euphrates all flourished, as well as destructed civilizations. each civilization had different uses for these rivers, however, some benefited more than others. when analyzing ancient civilizations, there   are things you must understand

explanation:

after the civil war, and with the termination of slavery, the south was faced with a big problem; what was supposed to happen and how they were supposed to deal with the freedom and the rights that black people and freed slaves had gained as a result of the north defeating the south and forcing the end of slavery. first, most, if not all, of the workforce of the south came from slaves and they did not have an option to replace the loss of said workforce. second, particularly in the south, people were convinced that black people were lesser, less intelligent, less capable and less smart than whites. this posed a huge problem for them. also, southerners were faced with another issue; freed slaves now had a say in how their lives would be lived and the right to politically choose the way they would be governed. people in the south did not want to accept this, none of this and this opposition and the conflicts that arose from it, not to mention the afereffects of the war, forced the congress of the time to enact and enforce the reconstruction plans that had been proposed by president andrew johnson.