REMOVE

1. boys
2. children
3. buildings (structures)
4. automobiles
5. sitting
6. artists (visual artists)

WHAT

1. Greenwich, Connecticut (1)
2. Visual Works (hierarchy n … (1)
3. black-and-white film (1)
4. bushes (1)
5. dogs (animals) (1)

More 

WHERE

1. Greenwich, Connecticut (1)

WHO

1. Clyfford Still; Still, Cl … (1)
2. Still, Clyfford (1)

WHEN

1. 1956 (1)
2. 1956 April 11 (1)