Answer to Question 1
d
Answer to Question 2
Music consisting merely of ideas for pieces the actual realization of which would either be impossible, ambiguous, or manifestly pointless.
The pieces often exist merely of instructions (word-scores)
Pauline Oliveros's Sonic Meditations
Take a walk at night. Walk so silently that the bottoms of your feet become ears and Become performers by not performing.
La Monte Young's Composition 1960 No. 9
consists of a straight line drawn on a piece of paper. It is to be performed and comes with no instructions.