This is a special case of SHM as there are 4 masses and 4 springs and they produce four resonant frequencies.
This case is different from one mass & several springs or several masses connected to one spring.
In the physical world, real systems have several springs & several masses in between the springs.
These are called higher order systems and have several natural frequencies.
Examples are a motor car, a building structure , bridge, rockets, aeroplanes etc.
In electron is too there are several induction, capacitor systems seperated by resistors and they form higher order filters (several natural frequencies).
The responses of these systems are found using differential equations.
Other ostracizes, flight of aeroplane etc.
Hence b is the correct answer.