In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.
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Sniffer dog Tucker uses (1)________ nose to help researchers find out why a killer whale population off the northwest coast of the United States is (2)________ the decline. He searches for whale faeces floating on the surface of the water, which are then collected for examination. He is one of the elite team members of detection dogs used by scientists studying a (3)________ of species including right whales and killer whales.
Conservation canines are fast becoming indispensable tools for biologists according to Aimee Hurt, associate director and co-founder of Working Dogs for Conservation, (4)________ in Three Forks, Montana. Over the last few years, though, so many new conservation dog projects have sprung up that Hurt can no (5)________ keep track of them all. Her organisation’s dogs and their handlers are fully booked to assist field researchers into 2012.