Which of the following scenarios best represents a constant rate of change? 1. Moore's law in computer science states that the number of transistors on integrated circuits doubles approximately every two years; 2. A deposit of $2500 into an account with an APR of 43.1% compounded monthly for 3 years. 3. A social media post goes viral, reaching twice as many users every hour for several hours. 4. A student's grades in school vary from semester to semester, depending on the difficulty of courses and personal circumstances. 5. Heating a pot of water steadily at 2 degrees Celsius per minute.