The carbon, oxygen, hydrogen and nitrogen are the key elements in aminoacids as all aminoacids contain amine (NH2) and carboxyl (COOH) as functional groups and R group for every specific aminoacid.
A sentence has been given in Active/Passive Voice. Out of the four given alternatives, select the one which best expresses the same sentence in Passive/Active Voice.
The operating system manages all the CPU, disc drives, establish a user interface, execute and provide services for applications software, printers, etc...