What maritime innovations and discoveries are attributed to Zheng He, who lived during the Ming dynasty?

A. Flexible rudder design, waterproof lacquers, triple sail system,
charting instruments
B. Charting of new sea currents, layered sails, stern rudders,
waterproof lacquers
C. Creation of new maps, central rudders, watertight compartments,
and advanced sails
D. Central rudders, watertight glass, triple sails, charted landscapes

i think they would live in caves or natural tunnels

i think it was   tsar alexander ii

in mcculloch v. maryland (1819) the supreme court ruled that congress had implied powers under the necessary and proper clause of article i, section 8 of the constitution to create the second bank of the united states and that the state of maryland lacked the power to tax the bank.

gibbons v. ogden, (1824), was a landmark decision in which the supreme court of the united states held that the power to regulate interstate commerce, granted to congress by the commerce clause of the united states constitution, encompassed the power to regulate navigation.