Boolean parameter values can be on, off, true, false, yes, no, 1, or 0, which are all case-insensitive. In addition, the first few characters of these values can be used as abbreviations if they are not ambiguous. That is, in addition to on, true, yes, and 1, t, y, and so on also represent true. If it is only o, it is not acceptable because it is ambiguous whether it is on or off.
For numeric parameters, you can use numbers and decimal points (for floating-point parameters), but you cannot use commas as thousands separator.
Units of time and memory parameters are case-sensitive. Time units must be all in lowercases, and for the memory units, k in kilobytes is in lowercase and all others are in uppercases. Also, the unit for minutes is min, not m.
The default units are not uniform, but are determined for each parameter, and they are stored in pg_settings.unit. You can check them by connecting to the database with psql and executing:
select name, unit from pg_settings where unit is not null;
The default units may vary; however, for example, even if a parameter has a default unit of kB, you can still add units to the parameter value as in '1MB' to specify 1 megabyte.


So the correct answers are A and D.