Read the following passage and choose the correct answer to indicate the correct word or phrase that best fits each of the numbered blanks.
Scientist Hayat Sindi's device is the size of a postage stamp, and it costs just a penny. But it could (1)________ millions of lives. In many parts of the world, doctors and nurses work with no (2)________ or clean water. They have to send health tests to labs and wait weeks for results. But this little piece of paper could change that. It (3)________ tiny holes that are filled with chemicals. These chemicals are able (4)________ health problems. A person places a single (5)________ of blood on the paper. The chemicals in the paper change (6)________ the blood and indicate (7)________ or not the person has an illness.