What Was the Supreme Court's Decision in National Labor Relations

What was the Supreme Court's decision in National Labor Relations Board v. Noel Canning?

A) Obama's appointments were unconstitutional because Congress has the power to decide when it is in session.
B) Obama's use of executive privilege was unconstitutional, but his appointments would be allowed to stand.
C) Since Obama's reliance on national security directives in this situation was unconstitutional, his appointments were also unconstitutional.
D) Obama misused executive proclamations in this situation, but his appointments would be allowed to stand.