正解:D
A /27 subnet mask has 32 IP addresses, of which 30 are usable for hosts. This is the smallest subnet that can accommodate 31 laptops, as the other options have either too few or too many IP addresses. A /27 subnet mask is equivalent to 255.255.255.224 in decimal notation, and has a wildcard mask of 0.0.0.31. The network address is 10.10.10.0, and the broadcast address is 10.10.10.31. The usable host range is 10.10.10.1 to 10.10.10.30.
Reference
1: Subnet Cheat Sheet - 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network Reference
2: IP Subnet Calculator