The two printmaking processes that use acid to remove lines in metal plates are _______.

a. wood engraving and linocut
b. engraving and etching
c. etching and aquatint
d. aquatint and lithography
e. screen printing and monotype

c. etching and aquatint

a. Incorrect. These are relief techniques for printmaking.
b. Incorrect. While etching does use acid to remove lines, engraving does not.
c. Correct. Both etching and aquatint use acid to remove lines from a metal plate.
d. Incorrect. While aquatint does use acid on metal, lithography uses a stone plate.
e. Incorrect. Neither screen printing nor monotype techniques use acid on metal.