I'm calculating the basis in connection with redeeming shares of an international stock mutual fund. The fund has paid dividends quarterly, which I reinvested. I'm reviewing the Federal 1099-DIV forms for each year I have owned the fund. In box 1a, the stated dividends include the actual dividends PLUS the foreign tax paid.
Question: In calculating the basis, do I use (a) only the actual dividends or (b) the dividends listed in box 1a of 1099-DIV, which adds in the foreign tax credit? [Of course, I take the foreign tax credit on Form 1040, line 47 in 2017.]