Final answer:
In a flowering plant, the sperm travels from the anther, where it is produced as pollen, to the stigma. This is followed by the growth of a pollen tube through the style leading to the ovule for fertilization, which is the route A. Anther to stigma.
Step-by-step explanation:
The route followed by a sperm from production to fertilization in a flowering plant comprises several steps, beginning with the production of pollen in the anther and ending with fertilization within the ovule. Initially, pollen is produced in the anther, which is the male reproductive part of the flower. The pistil, the female reproductive part that includes stigma, style, and ovary, enables this process. The pollen must be transferred to the stigma, where it germinates and the pollen tube begins to grow. This tube travels through the style and eventually reaches the ovule, where the sperm can fertilize the egg, resulting in a diploid zygote. This process, including the subsequent fusion of another sperm cell with the polar nuclei to form the triploid endosperm, is known as double fertilization.
Given the options provided in the question, the correct route for the sperm from production to fertilization is A. Anther to stigma. This journey continues with the pollen tube formation from the stigma through the style to reach the ovule.