To round 46,145 to the nearest thousand, follow these steps:

1. Look at the hundreds place (which is 1 in this case).
2. Since the hundreds digit is less than 5, round down.

Thus, 46,145 rounded to the nearest thousand is 46,000.

So, the correct answer is: 46,000.

Would you like more details on rounding or have any questions?

Here are 5 related questions to further explore rounding and estimation:

1. How do you round a number to the nearest hundred?
2. What is 78,625 rounded to the nearest thousand?
3. How would you round decimals, such as 46.145, to the nearest whole number?
4. Can you explain how to estimate sums by rounding each term?
5. How do you round numbers when the digit is exactly 5?

Tip: Always check the place value to the right of the place you're rounding to determine whether to round up or down.