What is the minimum length of the 'Options' field in an IPv4 header?

The minimum length of the 'Options' field in an IPv4 header is indeed 0 bits. This is because the Options field is not mandatory in every IPv4 packet. In fact, the base IPv4 header is 20 bytes (or 160 bits) long without any options included. The header can be extended with additional options, but if no options are required or included, the Options field simply doesn't take up any space, effectively making its minimum length 0 bits. This flexibility allows IPv4 to adapt to different networking needs, enabling the transmission of packets without the overhead of options when they are not necessary.