Answer:
Wind.
Step-by-step explanation:
Gymnosperms are also known as naked plants as their ovules are in the unfertilized state and their seeds do not bear fruits. Gymnosperms are known as seed plants.
Gymnosperms pollen grains are transferred from the pollen cone to the ovule. Their pollen are generally transferred by winds as they are lighter and resistant to water. Sometimes, insects are also responsible for the transfer of pollen grains.
Thus, the correct answer is option (b).