Involuntary contraction, twitching.

• A. -ology
• B. -sarcoma
• C. -plasia
• D. -spasm

Answer: (D)

Recognizing a suffix that denotes involuntary contraction. In medical terms, a spasm is a sudden, involuntary contraction of a muscle or group of muscles, which matches the description “involuntary contraction, twitching.” The suffix -spasm is used to describe these contractions, as in bronchospasm or laryngospasm. The other suffixes refer to different ideas: -ology means the study of something, -sarcoma is a malignant tumor of connective tissue, and -plasia means growth or formation of tissue. These do not convey the idea of an involuntary muscle contraction, so they aren’t correct for this definition.