A major objective of teaching English grammar is to

The correct option is "develop the ability to express ideas logically and correctly in speech and writing".

Step-by-Step Explanation:

1. Understanding the Role of Grammar: Grammar is the system of a language. It provides the structure, rules, and guidelines that dictate how words are combined to form sentences and convey meaning.

2. Analyzing the Options:
- "increase our ability to memorize rules": While learning grammar involves understanding rules, memorization for its own sake is not the ultimate objective of education. Rules are tools, not the end goal.
- "develop interest in studies": Although engaging teaching methods can spark interest in learning, this is a broad goal of all education and not a specific, major objective of teaching English grammar.
- "increase the originality of our ideas": Originality is related to creativity and critical thinking. While grammar helps organize and convey original ideas, grammar itself does not generate or increase the originality of those ideas.
- "develop the ability to express ideas logically and correctly in speech and writing": The primary function of grammar is to ensure effective communication. By mastering grammar, learners acquire the structural tools needed to organize their thoughts logically and convey them accurately to others, both when speaking and writing. This is the ultimate practical purpose of grammatical training.

3. Conclusion: Therefore, the major objective of teaching grammar is to enable learners to express their ideas clearly, logically, and correctly.