The correct answer is (b). Ultrasonics is a recently developed technique for monitoring foetal growth. It is a non-invasive technique that uses sound waves to create images of the foetus. This technique is safe for both the mother and the foetus, and it can be used to monitor the foetus’s growth, development, and position in the womb.
Microwave technique is a non-invasive technique that uses microwaves to create images of the foetus. However, this technique is not as safe as ultrasonics, and it is not as widely used.
Ultra-violet rays are a type of electromagnetic radiation that is harmful to both the mother and the foetus. They can cause birth defects and other health problems.
X-rays are a type of electromagnetic radiation that is also harmful to both the mother and the foetus. They can cause cancer and other health problems.