What is 45 × 0.1?

The correct answer is A) 4.5.

To explain: When you multiply 45 by 0.1, you are essentially finding 10% of 45. You can do the multiplication as follows:

45 × 0.1 = 4.5

This means that 0.1 times 45 gives you 4.5. If you have any more questions or need further assistance, feel free to ask!