He paid the dining bill . . . . . . . . a credit card.

The correct answer is Option D: with

Here's why:

We use the preposition "with" to indicate the instrument or means used to do something.

In this sentence, the credit card is the instrument used to pay the bill.

* "He paid the dining bill with a credit card" means he used a credit card as the method of payment.

Let's look at why the other options are incorrect:

* "for" is used to indicate a reason or purpose. "He paid the dining bill for his friend" would be correct, but not in this context.

* "in" is usually used to indicate location or a state of being. "He paid in cash" is possible, but "in a credit card" is grammatically incorrect.

* "by" is often used to indicate proximity or agency. "He paid by check" is also possible, similar usage of "with". However, "with" usually prefers to using an instrument or a tool.

Therefore, "with" is the most appropriate preposition to use in this sentence.