Comprehensive and Detailed In-Depth Explanation:

IPv4 address classes are defined as follows:

Class A: 1.0.0.0 – 126.255.255.255 (First bit = 0)

Class B: 128.0.0.0 – 191.255.255.255 (First two bits = 10)

Class C: 192.0.0.0 – 223.255.255.255 (First three bits = 110)

Correct Answer:

(B) 100.1.1.1 falls in the range 1.0.0.0 – 126.255.255.255, making it a Class A address.

Incorrect Options:

(A) 192.168.1.1 is a Class C address.

(C) 172.16.1.1 is a Class B address (172.16.0.0 – 172.31.255.255 is private).

(D) 127.1.1.1 is a reserved loopback address, not a public Class A address.