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[ Option B ]

Among the given options, Android Oreo is the most recent version.

• Android versions before Android 10 had dessert names in alphabetical order.
• After Android 9, Google stopped publicly using dessert names.

[ Option B ]

In operating systems, the fork() system call is used to create a new process called the child process. After calling fork(), both parent and child processes continue execution from the same point, but the return values help distinguish them.

When fork() is Successful:

• In the parent process, it returns the Process ID (PID) of the child process.
• In the child process, it returns 0.

[ Option A ]

In Unix/Linux systems, the cron command is used to schedule programs or tasks to run automatically at a specified time or at regular intervals. It works through a configuration file called crontab, where users can define when and which command should be executed.

• The nice is used to set process priority.
• The vmstat is used for system performance monitoring.
• The date and time are used to display or set system time.

[ Option D ]

A Service Level Agreement (SLA) is a contract between a cloud provider and a customer that defines expected service quality, availability, and responsibilities. SLAs are important for both the customer, who uses them to compare and choose services, and the provider, who clarifies obligations and limits liability.

[ Option D ]

In Linux, different commands are used for specific purposes related to system management and file handling. 

• The ps command is used to display the status of running processes. 
• The grep command searches for patterns within files. 
• The cat command is used to display or concatenate file contents.

However, the top command is used to display real-time information about system processes such as CPU and memory usage. It does not display the first few lines of a file. That function is performed by commands like head.

[ Option A ]

In Linux, scheduling tasks to run automatically at specific times, dates, or intervals is done using the cron (crontab) utility. It allows users to define jobs that will execute periodically, such as every minute, hour, day, or week. 
This mechanism is managed by the cron daemon, which reads the crontab file and executes tasks accordingly.

[ Option B ]

These Linux commands are executed step by step. First, mkdir a creates a directory named a, and cd a moves inside it. Then touch b and touch c create two empty files named b and c inside directory a.
Next, ls>d.txt lists all files in the directory (b and c) and stores this output in a file named d.txt. So, d.txt contains, bc.
Finally, grep "b" d.txt searches for lines containing b in the file d.txt. Since only one line contains b, the output will be b.

[ Option B ]

A Hypervisor is a software layer that enables virtualization, allowing multiple guest operating systems (OSs) to run simultaneously on a single physical machine. It manages and allocates hardware resources securely among the virtual machines (VMs), ensuring that each VM operates independently without interfering with others.
Hypervisors do not allow guest OSs to directly control hardware or run in kernel mode for managing devices.

[ Option C ]

In Unix/Linux systems, the mount command is used to attach a new file system to the existing directory structure. 
It makes the files and directories of the new storage device accessible at a specific directory called the mount point.