Testing for Concussions When a patient is suspected of having a concussion, or brain injury, doctors often turn to
computed tomography, or CT, scans to find out for sure. In a CT scan, a series of X-rays
is taken. Each one shows an individual "slice" of the brain, and they can be combined to
form a complete three-dimensional picture. Because of the amount of radiation patients
are exposed to, however, doctors question the use of the scans, especially for children.
Now researchers have proposed an alternative way of diagnosing head injuries: a simple
blood test. The test detects proteins that burst out of brain cells into the bloodstream
immediately after an injury. It allows doctors to determine whether a patient has suffered
head trauma and needs further treatment.
What is the main idea of the passage?

A: A new blood test makes it easier-and safer-to detect concussions.

B: Doctors commonly use CT scans to test for brain injuries.

C: A new blood test can identify proteins that are present in the blood following a
brain injury

Read the excerpt from the code book. without much hope of a theoretical breakthrough, cryptanalysts have been forced to look for a technological innovation. if there is no obvious way to reduce the number of steps required for factoring, then cryptanalysts need a technology that will perform these steps more quickly. silicon chips will continue to get faster as the years pass, doubling in speed roughly every eighteen months, but this is not enough to make a real impact on the speed of factoring—cryptanalysts require a technology that is billions of times faster than current computers. consequently, cryptanalysts are looking toward a radically new form of computer, the quantum computer. if scientists could build a quantum computer, it would be able to perform calculations with such enormous speed that it would make a modern supercomputer look like a broken abacus. the author’s purpose in this paragraph is to convince the readers to pursue a career in analysis. explain the need for faster technology in cryptanalysis. entertain with interesting stories about supercomputers. argue for more money to develop a quantum computer.