A barge must carry steel pieces for a construction project such that the total weight of the steel pieces is under 1,500,000 kilograms (kg). Each steel piece is either a beam, which weighs 363kg or a connector plate, which weights 6kg. There must be at least 2 connector plates for each beam. If b is the number of beams and c is the number of connector plates, which of the following systems of inequalities must be true? a. 363 +6c < 1,500,000
b <= 2c
b. 363 +6c >= 1,500,000
2b <= c
c. 363b + 6c >= 1,500,000
b >= 2c
d. 363b + 6c >= 1,500,000
2b >= c