What is a right angle probe primarily used for?

The right angle probe is primarily designed to feel cavity margins, which makes choice A the best answer. This instrument is essential in dental assessments, as it allows dental professionals to explore and assess the integrity of tooth surfaces, particularly in areas that may be compromised or have undergone decay. By feeling the margins of a cavity, the practitioner can evaluate whether the edges are well-defined or if there are any irregularities that need attention, ensuring proper treatment planning.

Other options, while related to different aspects of dental practice, do not reflect the primary function of the right angle probe. For example, placing dental materials typically requires different instruments that are specifically shaped for that purpose. Similarly, removing calculus deposits is best achieved with scalers or curettes, which are designed to efficiently detach calculus from the teeth. Lastly, identifying stains on teeth often involves visual examination and may use instruments like explorers, but it is not the primary function of the right angle probe. Therefore, the right angle probe's main utility in sensing cavity margins is crucial for effective diagnosis and treatment in dental practice.