What is a key assumption made in the Naive Bayes classification model?

The Naive Bayes classification model operates under the fundamental assumption that the features used for classification are independent of one another, given the target class. This means that the presence or absence of a feature does not influence the presence or absence of another feature. This assumption simplifies the computations involved in estimating the conditional probabilities required for classification, making Naive Bayes both efficient and effective in a wide range of applications, particularly for text classification tasks such as spam detection.

This independence assumption is deemed "naive" because, in reality, many features do display dependencies (for example, certain words may frequently occur together in a document). However, despite this simplification, Naive Bayes often performs surprisingly well in practice, especially with large datasets.

The other options do not capture the essence of the Naive Bayes model's assumptions. For instance, assuming that features are dependent contradicts the core principle of the Naive Bayes classifier. Claims about equal importance amongst features or that only the target variable influences the features do not reflect Naive Bayes' requirement regarding feature relationships and independence during classification.