题目选项分析

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

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.