Recent Presidents, Beginning with Reagan, Have Used Something Called "Signing

Recent presidents, beginning with Reagan, have used something called "signing statements" to expand presidential power.What has been notable about the expansion in the use of these statements?

A) Presidents have used them to reinterpret and sometimes nullify congressional law.
B) They have given executive agencies clear legal, or constitutional, permission to ignore congressional oversight.
C) Presidents have used them less as a way of negating congressional action, than clarifying congressional intent, after consultation with key lawmakers.
D) These have repeatedly excused illegal and unethical practices, including torture of foreign detainees in anti-terrorism activities.