In DNA, the complementary base pairing rules are:

• Adenine $(A)$ pairs with Thymine $(T)$
• Guanine $(G)$ pairs with Cytosine $(C)$

The question says: the compound "$A$" is a complementary base of ______ in DNA strands.

Here, "$A$" denotes Adenine.

In DNA, Adenine pairs with Thymine.

Now check the options:

• A: Uracil — found in RNA, not DNA pairing with adenine in DNA
• B: Guanine — pairs with cytosine
• C: Adenine — adenine does not pair with itself
• D: Cytosine — pairs with guanine

Therefore, the correct complementary base of adenine in DNA should be Thymine, but Thymine is not present in the options.

Hence, none of the given options is correct. The stored answer $\text{C}$ (Adenine) is incorrect.