Correct Option: B

A record route option is used to record the internet routers that handles the datagram. It can list up to nine router addresses. It can be used for debugging and management purpose. In IPv4, options and padding 40 bytes are allotted, maximum nine routers addresses are allowed. Each IPv4 address is 32 bits or 4 bytes.
So, ⇒ 4 × 9 = 36 bytes.
Extra byte are used for the option. Hence, the record route (RR) option field of an IPv4 header is (9).
Hence, 9 is correct answer.