To evaluate the expression 21.05347 - 1.6324 x 0.43 to 3 decimal places, we need to follow the order of operations. First, we need to perform the multiplication 1.6324 x 0.43, which gives us 0.701932. Then, we need to subtract this result from 21.05347, which gives us 21.05347 - 0.701932 = 20.351538.

Rounding this result to 3 decimal places, we get 20.352.

So, the correct answer is D. 20.352.