The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
He will make mistakes, but he will learn by making mistakes. So, dear parents, once you put the money in your children’s little pockets, forget all on it.

Correct option is A

In the given sentence, the segment (a) "children’s little pockets, forget all on it" contains a grammatical error.
The preposition "on" should be replaced with "about" to convey the correct meaning.
The corrected segment should be "children's little pockets, forget all about it." This correction makes the sentence coherent and grammatically correct.
To summarize, the corrected sentence would be: He will make mistakes, but he will learn by making mistakes. So, dear parents, once you put the money in your children's little pockets, forget all about it.