Read the statement regarding myofibril and choose the correct option
1. Each myofibril has alternate dark and light bands.
2. In the centre of each 'A' band is an elastic fibre called 'Z' -line 3. 'A' and 'I' bands are arranged alternately throughout the length of myofibril
4. Sarcomere is the functional unit of contraction
5. Central part of thick filament not overlapped by a thin filament is the 'M' line