Final answer:
The graph that represents Natasha's speed on her bicycle and time would start with a gentle slope uphill, transition to a flat line for a consistent speed on a flat road, and end with a steep slope downhill.
Step-by-step explanation:
The graph that shows the relationship between Natasha's speed on her bicycle and time would start with a gently sloping line representing her slow uphill speed for the first 5 minutes. Then, it would transition to a horizontal line representing her consistent speed on the flat road for the next 15 minutes. Finally, it would show a steeply sloping line representing her faster and faster speed during the last 7 minutes of her ride downhill.