S1: I was so eager not to disappoint my parents that I ran errands for anyone.
P: On the way a boy on a bicycle crashed into me and my left shoulder hurt so much that my eyes watered.
Q: Only then did I cry
R: But I still went and bought the maize, took it to my neighbours and then went home.
S: One day my neighbours asked me to buy some maize for them from the bazaar

The passage begins with the author expressing his eagerness to not disappoint his parents, which is why he frequently ran errands. This is followed by statement S, where the author mentions being asked by his neighbors to buy maize. Statement P then describes an accident that occurred during this errand. Despite the injury, the author continues with the task, which is highlighted in statement R. Finally, statement Q concludes the passage by showing that the author cried only after completing his responsibility, emphasizing his determination.

Thus, the correct sequence is S-P-R-Q, and the correct answer is option A.