The correct answer is option 'C' - I, II and III are all problems in teaching and learning of mathematics. Let's discuss each problem in detail:

I. Crude assessment:
- Crude assessment refers to the use of simplistic or insufficient methods to evaluate students' understanding and mastery of mathematical concepts.
- It can involve relying solely on written examinations that focus on rote memorization and procedural knowledge rather than deep understanding and problem-solving skills.
- This approach does not effectively capture the true extent of students' mathematical abilities and may lead to inaccurate assessments of their progress.
- Crude assessment can hinder students' motivation and engagement with mathematics, as they may perceive it as a repetitive and meaningless exercise.

II. Lack of interest:
- Many students develop a lack of interest in mathematics due to various factors, such as a perceived lack of relevance to their daily lives or negative experiences in the subject.
- When students are not interested in mathematics, they may struggle to engage with the content, leading to a lack of effort and motivation to learn.
- This lack of interest can hinder their ability to grasp new concepts, solve problems, and develop mathematical reasoning skills.
- Teachers need to employ engaging and interactive teaching methods, real-world applications, and relevant examples to spark students' interest in mathematics.

III. Inadequate teacher preparation:
- Teachers play a critical role in facilitating effective learning experiences for students.
- Inadequate preparation of teachers in terms of content knowledge, pedagogical strategies, and classroom management can significantly impact the teaching and learning of mathematics.
- Teachers need to have a deep understanding of mathematical concepts and be able to effectively communicate and explain them to students.
- They should also be familiar with various instructional strategies, problem-solving approaches, and assessment methods to cater to the diverse learning needs of students.
- Inadequately prepared teachers may struggle to deliver engaging and effective mathematics lessons, leading to students' disengagement and poor learning outcomes.

In conclusion, all three mentioned problems - crude assessment, lack of interest, and inadequate teacher preparation - contribute to the challenges faced in teaching and learning of mathematics. Addressing these problems requires a comprehensive approach that involves improved assessment methods, student-centered teaching practices, and enhanced teacher training and professional development.