Answer is 300, D.

Units Digit: 007, 017....097 = 10

Tens Digit: 070, 071...079 = 10

So there are 10 + 10 = 20 instances of 7 in each hundred numbers. So in 1000 numbers, there are 10 x 100 numbers = 20 x 10 = 200 instances of 7 in 1000 for units and tens digits.

Hundreds digit: 700, 701...799 = 100 instances of 7 for the hundreds digit.

So from 1-1000, there are 200 + 100 = 300 instances of 7.

Hope that helps!!!

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