Barney was experimenting with different effects on his camera and finally produced this photo. Which effect did Barney use in this photo? Barney used BLANK in this image.

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Silverpoint is a. a technique using the blackish residue of impure carbon obtained by removing water from animal and vegetation substances. b. a technique involving the use of a metal point, and a thin silver wire, popular in the 14th and 15th centuries. c. a printmaking technique born from crayon manner that imitates the appearance of chalk lines. d. a technique used since the 16th century involving a stick filled with either colored or black graphite, a heated mixture of carbon and clay