About HttpURLConnection's setDoInput

[Himai Minh]

In EPractice lab, there is a question like this:

 URL url = new URL(...);
 HttpURLConnection myConnection  =(HttpURLConnection) url.openConnection();
 myConnection.setRequestMethod("POST");
 myConnection.connect();
 OutputStream outStream = myConnection.getOutputStream();

What changes ensure this fragment works as intended?

//Only important words are shown:
Select one:
A. Both doInput and doOutput flags must be true to interact with web service provider. To achieve this, we must call setDoInput(true) and setDoOutput(true) method before obtaining connection.
B. Only doInput flag must be true....
C. Only doOutput flag must be true to interact with web service provider. To achieve this, we must call setDoOutput(true) method before obtaining connection.
D. Both doInput and doOutput flags must be false......

I believe C is the answer. By default, doInput flag is true. Even if we don't call setDoInput(true), this doInput flag is still true. And it won't harm if we call setDoInput(true). And it is not a must to call setDoInput(true). However, it is a must to call setDoOutput(true) because doOutput is false by default.

But the given answer is A.