Based on the information present in the given passage, you need to write a correct answer to the given question. A correct answer is one that correctly and completely answers the question. Do not write answers that address the question partially or incorrectly. The correct answer must be contained in the given paragraph.

Example input: Paragraph- Sent 1: Obama was born on August 4, 1961, at Kapiʻolani Maternity & Gynecological Hospital in Honolulu, Hawaii.
Sent 2: He is the only President to have been born in Hawaii.
Sent 3: He was born to a white mother and a black father.
Sent 4: His mother, Ann Dunham (1942-1995), was born in Wichita, Kansas, of mostly English descent, with some German, Irish, Scottish, Swiss, and Welsh ancestry. Question: How old was Obama's mother when he was born?
Example output: 19.
Example explanation: Obama was born in 1961. His mother was born in 1942 and 1961-1942=19. Therefore, any of the following responses are considred correct: '19' and 'almost twenty'.
Q: Paragraph- Sent 1: Plants also detect the daily cycle of light and darkness.
Sent 2: Do you know how plants respond to these changes?
Sent 3: Some plants open their leaves during the day.
Sent 4: It is during these hours the plant can collect sunlight.
Sent 5: At night, the plant closes its leaves to prevent water loss.
Sent 6: Many plants respond to the change in the length of the day.
Sent 7: As days grow shorter, some plants respond by going dormant.
Sent 8: Dormant is when a plant suspends its growth.
Sent 9: It does this in order to survive.
Sent 10: Shorter days signal the coming of winter.
Sent 11: Winter in most areas means extreme cold.
Sent 12: It is also very dry in the winter months.
Sent 13: As winter approaches, some plants respond by their leaves changing color.
Sent 14: After the change in color, they fall off.
Sent 15: This dormancy period helps trees.
Sent 16: It allows them to survive the cold and dry winter.
Sent 17: Plants only want to grow when conditions are right. 
Question: What are two ways we might suspect a tree has become dormant?.
A:
Its growth has stopped and the leaves have fallen off.