In a democracy, individual differences are encouraged because they lead to a diverse range of beneficial contributions to the common cause. This means that when individuals have different opinions, perspectives, and experiences, they are more likely to bring unique ideas and solutions to problems.

Option 1 suggests that individuals in a democracy will prioritize the good of the nation over their own preferences. While this can be true to some extent, it doesn`t directly address the importance of individual differences and how they contribute to the overall benefit of society.

Option 2 states that individuals in a democracy will tend to act and think alike in the long run. However, this contradicts the essence of democracy, which values individual freedom and diversity of thought.

Option 4 claims that the Constitution guarantees the right of the individual to act as they please. Although this may be true, it doesn`t explain why individual differences are specifically encouraged in a democracy.

Overall, option 3 is the most accurate explanation as it acknowledges that individual differences are valuable in a democracy because they lead to a wider range of beneficial contributions to society.