Final answer:
Marriage within the Jain religion is considered forbidden for monks and nuns due to their vows of celibacy, whereas for lay Jains, marriage is optional but generally discouraged to limit attachments.
Step-by-step explanation:
Due to vows renouncing sexual pleasures and all attachments, which statement best describes marriage within the Jain religion is that marriage is considered C. Forbidden. In Jainism, monks and nuns adopt celibacy as a part of their practice to avoid attachment, which is a core principle of the religion. Lay Jains, or householders, are encouraged to practice chastity or to limit sexual activity for spiritual growth. However, they are not typically required to completely renounce marriage. Therefore, the right answer to the question for monks and nuns would certainly be 'Forbidden,' but for lay Jains, it is more accurate to say that marriage is 'Optional but discouraged' rather than strictly forbidden. It's important to understand that the approaches to marriage can vary among different individuals within the religion based on their level of adherence to Jain principles.