Answer:
1. Unity: To live the essential mark of unity, you can strive to be a peacemaker in your school and family, and avoid gossip or negative talk about others. You can also seek to build bridges between different groups at school and in your family, and celebrate each other’s unique gifts and talents.
2. Holiness: To live out the essential mark of holiness, you can set aside time each day to pray and be in conversation with God. You can also practice good stewardship of your time and money, and strive to live a life of integrity and virtue.
3. Catholicity: To live out the essential mark of catholicity, you can learn about and celebrate the diversity of cultures and beliefs that make up the Church. You can also attend Mass or other liturgies in different languages and traditions, and invite others to join you in worship.
4. Apostolicity: To live out the essential mark of apostolicity, you can share the Good News of Jesus Christ with others by living out your faith in practical ways. You can also get involved in service projects in your school or community, and look for opportunities to share your faith with your family and friends.