Final answer:
Jean-Michel Basquiat's signature painting style encompasses obsessive scribbling, elusive symbols and diagrams, and mask-and-skull imagery, reflecting his unique and influential Neo-expressionist approach to art.
Step-by-step explanation:
The signature painting style of Jean-Michel Basquiat includes all of the options listed - obsessive scribbling, elusive symbols and diagrams, and mask-and-skull imagery. Basquiat's work is known for its raw intensity and the blending of different kinds of visual information and iconography. He often incorporated words and phrases, and his paintings reflected a deep engagement with a range of subjects from anatomy to history, often touching on themes of identity, socio-political issues, and human mortality. His spontaneous, energetic approach, and use of unconventional materials and methods, combined with his Neo-expressionist style, made his work unique and highly influential.