Let the frequency of $A$ be $v$

$\therefore v_B=v+\frac{3}{100}v$

$v_C=v-\frac{3}{100}v$

$\therefore$ Beat frequency between $B$ and $C$

$=v_B-v_C$

$=\frac{3v}{100}+\frac{2v}{100}=\frac{5v}{100}=\frac{v}{20}$

$\frac{v}{20}=8$

$\Rightarrow v=160Hz$

Hence, the correct option is (D).

Statement (1) is correct. The photocopy machines emit UV radiations, which can cause eye problems.

Statement (2) is wrong. Infrared thermography (IRT), thermal imaging, and thermal video are examples of infrared imaging science. Thermographic cameras usually detect radiation in the long-infrared range of the electromagnetic spectrum (roughly 9,000–14,000 nanometers or 9–14 µm) and produce images of that radiation, called thermograms.

Statement (3) is correct. CT scan uses computer-processed X- rays and generates a three-dimensional image of specific areas of the body.

Hence, the correct option is (C).

When you considered it a large distance and measuring the justice Mall section of it then it can be considered to be a plane wavefront source at Infinity 

For example, the one coming from the sun to earth surface is considered to be plain VU friend from light diverging from a point source will be spherical

So, the wavefront due to a source situated at infinity is planar.

Hence, the correct option is (C).

When a pebble is thrown in still water, a circular pattern of alternate crests spread out. The kinetic energy makes the particles oscillate which comes in contact with it. The energy gets transferred to the particles of the next layer which also begins to oscillate. Thus it is the disturbance or waves that move forward and not the particles of the medium.

Hence, the correct option is (B).