[求助]GWD30 20

Researchers have announced that the magnetic fields emitted by one manufacturer’s security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers and that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.

1. of which type there are 200,000 worldwide, can interfere with pacemakers and that
2. of which, worldwide, there are 200,000 of that type, and which can interfere with pacemakers, and
3. of which type there are 200,000 worldwide, they can interfere with pacemakers and
4. 200,000 of which type exist worldwide, interfering with pacemakers, and
5. 200,000 of that type existing worldwide and can interfere with pacemakers, and

答案是D， 我在AD之间徘徊不定。不知道为什么选出D的。请指教。

怎么都不可能是D

个人倾向于A

Researchers have announced that the magnetic fields emitted by one manufacturer’s security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers and that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.

1. of which type there are 200,000 worldwide, can interfere with pacemakers and that
           
2. of which, worldwide, there are 200,000 of that type, and which can interfere with pacemakers, and
           
3. of which type there are 200,000 worldwide, they can interfere with pacemakers and
           
4. 200,000 of which type exist worldwide, interfering with pacemakers, and
           
5. 200,000 of that type existing worldwide and can interfere with pacemakers, and

A:  researcher have announced that magnatic fields can interference with pacemaker and that this interaction can bring......

So it should be "A"

明白了，谢谢！