Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

A ghostly animal creeps silently through a Florida swamp. It’s a rare type of big cat known as a Florida panther, one of only 80 to 100 such panthers left in the world. Scientists must work to save these remaining panthers from extinction, but their secretive nature is making it difficult. They are attaching a special transmitter to each Florida panther so they can follow their movements, range, and habits. The technology these transmitters use is called satellite tracking.

The scientists are dedicated professionals, but they are not pioneers. Their colleagues before them have attached tiny transmitters to many different kinds of wild animals, including birds, fish, and big cats. So the Florida scientists are using their methods. Firstly, they must trap and tranquillize the panther. Then, the transmitter is attached to a harness and strapped to the panther’s body. Each harness is custom designed and manually adjusted for panthers so it fits comfortably. Scientists don’t want the transmitter to interfere with the panther’s natural habits. The point of tracking them is to find out as much as they can about their natural habits.

Once the tracking transmitter is in place, the information it records is sent to an orbiting satellite. The satellite can see the transmitter that is attached to the panther, even when it is out of sight of a biologist on the ground. The satellite collects information from the transmitter about the

panther’s exact location. Once the information is received, it is transmitted back to Earth so it can be recorded by the scientists.

Scientists can use the information in many different ways. They can follow the panthers on the ground and observe their behavior. Alternatively, they can use the information to determine the panthers’ ranges and to understand their social patterns. They can also track how environmental changes like weather conditions affect their movements and health. All this information can be used to provide ideal conditions for the endangered panthers. It can also be used to protect the panthers from danger.

In the end, the panther silently slips away through the trees. Around its shoulders a transmitter is sending signals via satellite to a dedicated biologist. The biologist is using the information the transmitter provides to save the Florida panthers from extinction. With the help of satellite tracking these beautiful cats have a better chance of survival in the modern world.

The phrase "custom designed" in paragraph 2 probably means .

The harder he studies,__________