What does this Zig snippet output?

1const std = @import("std");
2pub fn main() void {
3    const a: ?u32 = 10;
4    const b: u32 = a orelse 99;
5    std.debug.print("{d}\n", .{b});
6    const c: ?u32 = null;
7    const d: u32 = c orelse 99;
8    std.debug.print("{d}\n", .{d});
9}