The correct answer is A. m + tc.
A binary BCH code is a linear error-correcting code that can correct up to t errors. The code is constructed by taking a polynomial of degree m and dividing it by a polynomial of degree t. The quotient is the codeword, and the remainder is the syndrome. The syndrome is used to determine the error pattern that has occurred.
The number of parity check bits is m + tc. This is because the codeword has length n, and the syndrome has length t. The parity check bits are used to ensure that the codeword is valid.
Option B is incorrect because it does not take into account the syndrome. Option C is incorrect because it does not take into account the length of the codeword. Option D is incorrect because it does not take into account the number of errors that can be corrected.