In his 1972 piece "Deadman" which took place outside a gallery, Chris Burden was lying on the street under a tarp with two flares around his head. When the police asked him what he thought he was doing, Burden responded by saying that...?

Burden responded by saying that "HE WAS MAKING A PIECE OF SCULPTURE".

Explanation: Christopher Lee Burden, who is know as Chris Burden was an American artist who live from April 11, 1946 to May 10, 2015 works in sculpture, installation, and performance art.

He was known with his performance called Deadman, which was acted at Mizuno gallery, Los Angeles, in November 12, 1972. He arranged with his friend to shot him on his arm with a small caliber riffle. During his performance outside the gallery, where he laid down on the street, the police asked him what he was doing, he responded that he was making sculpture. Which was exactly what he knew he was doing.

He was making a piece of art sculpture

Explanation:

According to Chris Burden's 1972 piece "Deadman", which took place outside a gallery, he was laying in the street, on La Cienega Boulevard in Los Angeles, which was next to a parked car in the lane, he was covered with a tarp, and there were two flares around him, when the cops came and asked him what he thought he was doing, he responded by saying he was making a piece of sculpture