Read the excerpt from the code book. although traffic analysis, tempest attacks, viruses and trojan horses are all useful techniques for gathering information, cryptanalysts realize that their real goal is to find a way of cracking the rsa cipher, the cornerstone of modern encryption. the rsa cipher is used to protect the most important military, diplomatic, commercial and criminal communications—exactly the messages that intelligence gathering organizations want to decipher. if they are to challenge strong rsa encryption, cryptanalysts will need to make a major theoretical or technological breakthrough. what is the central idea of this paragraph?

d is the correct answer. it recognizes the authors, allows for royalties to have their fair share of profit, and confirms validity.

because it’s a name of something popular we’ll know place

"birches" was written by the american poet robert frost. it was included in frost's third collection of poetry mountain interval. it was published in 1916. containing 59 lines, it is one of robert frost's most famous poems. as well as with other poems that deal with country landscape and wildlife, it represents frost as a naturalist writer.

for me, the most memorable literary image that frost uses in his poem is: “like girls on hands and knees that throw their hair before them over their heads to dry in the sun.” in this excerpt the author is comparing the trees to the beautiful image of girls drying their hairs to the sun and one cannot representing the image in our minds. this mental image is so strong due to the vivid description made in earlier lines of the poem where the author depicts the image of the snow set on the trees: “soon the sun's warmth makes them shed crystal shells shattering and avalanching on the snow-crust—such heaps of broken glass to sweep away you'd think the inner dome of heaven had fallen.” by so vividly describing the power that the winter climate has over the tree’s constitution, the author intends to define the magnificence of the birches (this kind of tree) as they withstand the power of the inclement nature. the author presents this image to us understand the very reason for the birches to be bent over, the main characteristic of the trees presented in the poem.