The correct option to complete the sentence "There were so many children ...." is A. that she couldn't feed them all. Let's break down why this is the correct choice and analyze the other options. Step-by-Step Explanation

1. Understanding the Sentence Structure:
2. The sentence begins with "There were so many children," which indicates a large quantity of children. The phrase that follows should logically express a consequence or result of this large number.
3. Analyzing Option A:
4. A. that she couldn't feed them all: This option correctly uses "that" to introduce a clause explaining the consequence of having so many children. It implies that the number of children exceeded her ability to feed them, which makes sense in the context. The phrase "couldn't feed them all" clearly indicates a limitation due to the large number of children.
5. Analyzing Option B:
6. B. than she could feed: This option uses "than," which is typically used for comparisons. The structure here is incorrect because it suggests a comparison rather than a consequence. The sentence would imply that there is a specific number of children she could feed, but it does not logically follow from the initial statement about the large number of children.
7. Analyzing Option C:
8. C. that she couldn't feed: While this option is similar to A, it is incomplete. The phrase "that she couldn't feed" lacks the word "them all," which is necessary to convey the full meaning. It leaves the reader hanging, as it does not specify what she couldn't feed. Therefore, it is less effective than option A.
9. Analyzing Option D:
10. D. that she could feed them all: This option suggests that despite the large number of children, she could feed all of them. This contradicts the implication of the first part of the sentence, which suggests a limitation due to the overwhelming number of children. Thus, it does not logically follow from the premise.

Summary of Why Option A is Correct

• Option A effectively communicates the idea that the number of children was so great that it exceeded her capacity to feed them, which is a logical consequence of having "so many children."
• The use of "that" introduces a dependent clause that explains the situation clearly and completely.

Revision Summary

• Correct Answer: A. that she couldn't feed them all.
• Option A indicates a consequence of having too many children.
• Option B incorrectly uses "than" for comparison, which is not suitable here.
• Options C and D either lack completeness or contradict the initial statement.

By understanding the structure and implications of each option, you can better grasp how to choose the most suitable completion for sentences in English.