Final answer:
The correct answer is d) Obligation. All Saint's Day is considered a holy day of obligation, where Catholics are required to attend Mass.
Step-by-step explanation:
If you're Catholic, attend Mass on All Saint's Day, as it's a "holy day of Obligation".
All Saint's Day, which takes place on November 1st, is a significant day in the liturgical calendar for Catholics around the world. It is a day when Catholics honor all saints, known and unknown. As outlined by the Catholic Church, there are certain days in the year, apart from Sundays, on which the faithful are obliged to participate in the Mass; these days are known as holy days of obligation. Therefore, the correct answer to the question is d) Obligation.