A 38-year-old woman complains of cold, painful fingertips, as well as difficulty swallowing and indigestion. Physical examination is remarkable for a thickened, shiny epidermis over the entire body, with restriction of movement of the extremities, particularly the fingers, which appear claw-like. Which of the following autoantibodies is likely to be found in this patient's serum? A. Anti-DNA topoisomerase I (anti-Scl-70) B. Anti-double-stranded DNA (ds DNA) C. Anti-IgG D. Anti-Sm E. Anti-SS-A