Answer:
C, proprietary software
Explanation:
Proprietary software, also known as non-free software, is computer software for which the software's publisher or another person reserves some rights from licensees to use, modify, share modifications, or share the software. It sometimes includes patent rights.
66,73 73-66=7
13,21 21-13=8
10,20 20-10=10
the missing no. is 9 so
52+9=61.
the pattern is
66,73,13,21,52,61,10,20
Answer: Python
Explanation: All I know is that the programming language is Python.
<span>Not a valid IPv6 address
A valid IPv6 address consist of 8 groups of 4 hexadecimal numbers separated by colons ":". But that can make for a rather long address of 39 characters. So you're allowed to abbreviate an IPv6 address by getting rid of superfluous zeros. The superfluous zeros are leading zeros in each group of 4 digits, but you have to leave at least one digit in each group. The final elimination of 1 or more groups of all zeros is to use a double colon "::" to replace one or more groups of all zeros. But you can only do that once. Otherwise, it results in an ambiguous IP address. For the example of 2001:1d5::30a::1, there are two such omissions, meaning that the address can be any of
2001:1d5:0:30a:0:0:0:1
2001:1d5:0:0:30a:0:0:1
2001:1d5:0:0:0:30a:0:1
And since you can't determine which it is, it's not a valid IP address.</span>