Muscle contraction is triggered
A) in response to an increase in the cytoplasmic Ca2+ concentration.
B) in response to a decrease in the cytoplasmic Ca2+ concentration.
C) in response to an increase in the cytoplasmic cAMP concentration.
D) in response to a decrease in the cytoplasmic cAMP concentration.
E) in response to an increase in the cytoplasmic titin concentration.
Answer: A) in response to an increase in the cytoplasmic Ca2+ concentration.