Final answer:
The reason that a pumpkin will not always become a large pumpkin is that pumpkins are not always pollinated properly, planted in the right conditions, or watered properly.
Step-by-step explanation:
The reason that supports the claim that a pumpkin will not always become a large pumpkin is (d) All of the above. This means that pumpkins are not always pollinated properly, pumpkins are not always planted in the right conditions, and pumpkins are not always watered properly. All of these factors can affect the growth and development of a pumpkin, leading to it not becoming a large pumpkin.