The correct answer is option 'A': To ask him to leave the school.

Explanation:
Einstein was summoned by the head teacher to ask him to leave the school. There were several reasons for this decision.

1. Disruptive behavior:
Einstein was known to be a rebellious student who often challenged authority. He questioned the traditional teaching methods and was not afraid to express his opinions. This behavior was seen as disruptive and disrespectful by the school administration.

2. Lack of interest in traditional subjects:
Einstein had little interest in subjects like history, languages, and literature, which were considered important by the school. Instead, he was more focused on mathematics and physics, which he found fascinating. This divergence of interests further contributed to the decision to ask him to leave.

3. Poor academic performance:
Einstein's unconventional approach to learning and his disinterest in traditional subjects resulted in poor academic performance. He often neglected his studies in favor of pursuing his own interests. This lack of commitment to his schoolwork was another factor that led to his dismissal.

4. Incompatible teaching style:
The school's teaching style was based on rote learning and memorization, which did not align with Einstein's preference for understanding concepts deeply. He found this method of instruction boring and ineffective, and it hindered his ability to excel academically.

Overall, Einstein's rebellious nature, lack of interest in traditional subjects, poor academic performance, and incompatible teaching style were the key reasons why he was summoned by the head teacher and eventually asked to leave the school. This decision turned out to be a turning point in Einstein's life, as he later went on to become one of the greatest physicists in history.