Topic: Sentence (বাক্য),

Best Answer Explained in Below-:

The question "Mark began to work in the aircraft industry" provides a clear and specific context about Mark's actions. When analyzing the available options, option C ("What did Mark begin to do?") directly corresponds to the information given. It seeks to clarify the nature of Mark's actions—specifically, that he started a position or career within the aircraft industry.

The other options, however, either ask for information not directly addressed in the statement (like Mark's birth or when he finished working), or they complicate the query unnecessarily. For example, option A ("When was Mark born?") has no relevance to Mark's career choices, and option D ("How old was he when he worked in the aircraft industry?") assumes additional details about Mark's age that are not provided. Meanwhile, option B ("When did he finish to work in the aircraft?") implies a conclusion or endpoint to an unnamed activity that is not mentioned in the initial statement.

Thus, option C is the only choice that correctly seeks clarification on the action Mark undertook—beginning his work in the aircraft industry—making it the most logical and relevant question among the options.