Missing choices:
a) Calcium entry into the sarcoplasm, calcium binds to troponin, muscle contracts, closing of calcium channels, calcium released from troponin, muscle relaxes
b) Calcium entry into the sarcoplasm, muscle contracts, calcium binds to troponin, closing of calcium channels, calcium released from troponin, muscle relaxes
c) Calcium entry into the sarcoplasm, calcium released from troponin, muscle contracts, closing of calcium channels, calcium binds to troponin, muscle relaxes
d) Calcium entry into the sarcoplasm, closing of calcium channels, calcium binds to troponin, muscle contracts, calcium released from troponin, muscle relaxes
My answer: d) Calcium entry into the sarcoplasm, closing of calcium channels, calcium binds to troponin, muscle contracts, calcium released from troponin, muscle relaxes