USB thumb drives (also called flash drives) serve several practical purposes in networking:
File Transfer: They are excellent for transferring Cisco router or switch configuration files between the device and a PC. This allows you to back up configurations, easily restore configurations, or work with them offline.
IOS Image Storage: USB thumb drives are convenient for storing and transferring Cisco IOS images, especially when you need to upgrade or recover network devices.
Why other options are incorrect:
to save the system log: While you might temporarily store log files on a USB drive, routers and switches generally utilize internal memory or a remote syslog server for logging purposes.
to save router hardware information: Hardware inventory information obtained from commands like show inventory is often copied and pasted to text files, which can then be stored on a USB drive. However, the drive itself doesn't directly save or store this hardware information.
to increase system memory: USB drives are not designed to act as additional system memory (RAM) for a router or switch.

The copy startup-config running-config command is used during the password recovery process on a Cisco router to load the saved configuration into the device's active running configuration. Here's why this is the correct choice:
Password Recovery Context: Password recovery often involves booting into ROMmon mode and changing the configuration register to bypass the normal boot process. This leaves the device with a blank running configuration.
Restoring Configuration: The copy startup-config running-config command copies the stored configuration (startup-config) from NVRAM into the running-config, which is used by the router for its operations.
Why other options are incorrect:
load_helper: While the load_helper command sometimes appears in password recovery procedures, it's typically used for older models and may not be necessary for all Cisco routers.
configure terminal: This command simply enters global configuration mode. It doesn't directly load a configuration.
copy running-config startup-config: This command saves the active running configuration into NVRAM as the startup-config. It's the reverse of what you need for password recovery.

To assign a static IP address to the Ethernet port on a computer, particularly in a Windows environment, you would navigate to the Network and Sharing Center. From there, you would access the adapter settings, select your local area connection, and then enter the properties for Internet Protocol Version 4 (TCP/IPv4). Within the properties, you would choose the option to use a specific IP address and enter the desired IP information, including the IP address, subnet mask, and default gateway. This process sets a static IP address for the Ethernet port, ensuring that the computer will always use the same IP address every time it connects to the network, which is useful for various network configurations and applications. Reference := How to Assign a Static IP Address in Windows 10 or Windows 11 - How-To Geek, How to Set Up a Static IP Address | PCMag