The correct answer is D. No article.
The word “dollar” is a non-count noun, which means it does not have a plural form and is not preceded by an article. For example, you would not say “I have two dollars” or “I saw a dollar on the ground.” Instead, you would say “I have two dollars’ worth of candy” or “I saw a dollar bill on the ground.”
In the sentence “Please lend me dollar,” the speaker is asking for a small amount of money. Since the amount of money is not specified, it is not necessary to use an article.
The other options are incorrect because they are all articles. A and An are indefinite articles, which are used to refer to a general or unspecified thing. The is a definite article, which is used to refer to a specific thing. In the sentence “Please lend me dollar,” the speaker is not referring to a specific dollar, so it is not necessary to use a definite article.
I hope this explanation is helpful. Please let me know if you have any other questions.