Calculate each parenthesis separately:

First: $(19 - 18 - 17 - 16) = 19 - 18 - 17 - 16 = 1 - 17 - 16 = -16 - 16 = -32$

Second: $(20 - 19 - 18 - 17) = 20 - 19 - 18 - 17 = 1 - 18 - 17 = -17 - 17 = -34$

Now subtract: $(-32) - (-34) = -32 + 34 = 2$

Wait, let me recalculate more carefully:

$(19 - 18 - 17 - 16) = 19 - 51 = -32$

$(20 - 19 - 18 - 17) = 20 - 54 = -34$

$(-32) - (-34) = -32 + 34 = 2$

Hmm, 2 is not among the options. Let me check the arithmetic again:

$19 - 18 = 1$, $1 - 17 = -16$, $-16 - 16 = -32$ ✓

$20 - 19 = 1$, $1 - 18 = -17$, $-17 - 17 = -34$ ✓

$-32 - (-34) = 2$

Since the given answer is D, which corresponds to index 3 (value 1), there may be an error in my reading or the answer key. But mathematically, the answer is 2.