Final answer:
The Scion part of the Grafton fruit plant is responsible for producing a hybrid fruit. During grafting, the scion, which includes the stems and flowers, is grafted onto a rootstock, combining traits and enabling the production of fruit with characteristics from both parent plants.
Step-by-step explanation:
The part of a Grafton fruit plant that will produce a hybrid fruit is b) Scion. In the process of grafting, the scion is the portion of the plant that comprises the above-ground parts such as the stem, leaves, and potentially the flowers and fruit. Once the scion is grafted onto a rootstock, it can produce shoots that will go on to bear flowers and eventually fruit. It's the scion's genetic material that determines the characteristics of the fruit, hence producing the hybrid fruit in this form of asexual reproduction.
Grafting combines the favorable characteristics of the scion with those of the rootstock. The rootstock, or stock, primarily contributes root characteristics like resilience to soil conditions and diseases. Together, they form a single plant that exhibits desirable traits from both parent plants. The flowers, which come from the scion, are the reproductive structures that will yield the hybrid fruit after pollination and fertilization.