The answer is:
4. scissors
The correct spelling for the rest is:
1. deficency-deficiency
2. labratoey-laboratory
3.psychiatry-psychiatry
Have you tried mouth numbing?
It's trachea, not tranchea xD
If your cilia which is located in your trachea got damaged, you will get sick easily. The reason is that the cilia helps protects you from bacteriam by keeping bacteria from getting down into your throat.
The cilia getting damaged is most common in smokers due to cigarette smoking, btw.
