How is thermohaline circulation influenced by salinity and temperature?

a. It is driven by density gradients, which are affected by salinity and temperature, with cold water and water with higher salt concentrations being more dense.

b. It is driven by density gradients, which are affected by salinity and temperature, with warm water and water with higher salt concentrations being more dense.

c. It is driven by density gradients, which are affected by salinity and temperature, with warm water and water with lower salt concentrations being more dense.

d. It is driven by density gradients, which are affected by salinity and temperature, with cold water and water with lower salt concentrations being more dense.