Here are the corrections for each sentence:

1. **Correct Answer:** B (remove "are": "Having leisure activities is truly important to the elderly.")

2. **Correct Answer:** D (change "staying" to "to stay": "Although she wanted to go to the museum, she decided to stay at home.")

3. **Correct Answer:** D (change "on screens" to "in front of screens": "Parents are concerned that their kids may be spending too much time in front of screens.")

4. **Correct Answer:** D (change "relaxed" to "relaxing": "Collecting coins is exciting, but it can also be relaxing.")

5. **Correct Answer:** B (change "lowly" to "slowly": "A camel runs much more slowly than a horse.")

Let me know if you need further assistance!