Both Odin and Go have the "zero is default" choice. Every type must have a default and that's what zero signifies for that type. In practice some types shouldn't have such a default, so in these languages that zero state becomes a sentinel value - a value notionally of this type but in fact invalid, just like Hoare's NULL pointer, which means anywhere you didn't check for it, you mustn't assume you have a valid value of that type. Sometimes it is named "null" but even if not it's the same problem.

Even ignoring the practical consequences, this means the programmer probably doesn't understand what their code does, because there are unstated assumptions all over the codebase because their type system doesn't do a good job of writing down what was meant. Almost might as well use B (which doesn't have types).