Final answer:
Petunia is known to have a self-incompatibility system and can only be pollinated by pollen from a genetically different plant that does not share the same S allele. The correct option for a flower with self-incompatibility that will be pollinated is (b) Petunia.
Step-by-step explanation:
The flowers that exhibit self-incompatibility have developed mechanisms to prevent pollen from the same flower or plant from fertilizing its own ovules. Petunia is known to have a well-studied self-incompatibility system. The mechanism involves a complex interaction between pollen and the stigma of the flower, primarily controlled by the S (sterility) locus. If the pollen carries the same S allele as the stigma, the plant recognizes it as self-pollen and inhibits its growth, leading to pollen tube death through apoptosis or ribonuclease activity.
Consequently, for a flower that has self-incompatibility to be pollinated, it must receive pollen from a genetically different plant that does not share the same S allele. Given the listed options (Sunflower, Petunia, Rose, and Orchid), and based on the provided information, Petunia has a well-documented system of self-incompatibility, implying that it would be the flower that would be successfully cross-pollinated by a genetically compatible different plant.
The correct option in the final answer is (b) Petunia.