Which command line switch would be used in NMAP to perform operating system detection?

Botnets are networks of compromised computers that are controlled remotely and surreptitiously by one or more cyber criminals. How do cyber criminals infect a victim's computer with bots? (Select 4 answers)

A Trojan horse is a destructive program that masquerades as a benign application. The software initially appears to perform a desirable function for the user prior to installation and/or execution, but in addition to the expected function steals information or harms the system.

The challenge for an attacker is to send a convincing file attachment to the victim, which gets easily executed on the victim machine without raising any suspicion. Today's end users are quite knowledgeable about malwares and viruses. Instead of sending games and fun executables, Hackers today are quite successful in spreading the Trojans using Rogue security software.
What is Rogue security software?

You run nmap port Scan on 10.0.0.5 and attempt to gain banner/server information from services running on ports 21, 110 and 123.
Here is the output of your scan results:

Which of the following nmap command did you run?

What are the default passwords used by SNMP? (Choose two.)