When light enters a lens, C) it is refracted.
Since it is bent when it enters a lens, it has to be refracted.
Answer:

Explanation:
Given that,
A system can detect objects as small as 19.1 cm i.e. 0.191 m. It is the wavelength.
We know that,
Frequency, 
So,

So, the frequency of such a system is equal to
.
Answer:
A and C is about 12 cm away from each other.
Explanation: