This seems easy.. You got this.
Population and nutrients, This is because if you have a large population then you must need a certain amount of nutrients to suit the population
Sporophyte generation - It is found in both seed and seedless plant. Dominant phase of the life cycle of the seedless plants is diploid sporophyte while in seed plant male and female gametes fuses to produces a diploid zygote which develops into a sporophyte.
Pollination - It occurs in seed plants only
Sporophyte contains male and female reproductive structures - It is found in both seed and seedless plant.
Single fertilization - It occurs in both seed and seedless plant
Sperm cells transported by water to egg cells - seedless plant only
I believe the answer is B, primary active transport. Root hair cells in plant use active transport to absorb mineral ions such as nitrates from the soil. The concentrations of minerals in the soil are lower in the soil than in within the root hair cell, therefore the transport will be against the concentration gradient which does not favor diffusion, therefore the pant has to use active transport.