The correct answer is: A. Information bits
In Minimum Distance Separable (MDS) codes, the minimum distance is one more than the number of information bits. This means that any two codewords in an MDS code must differ in at least one information bit. This property makes MDS codes very robust to errors, as any single error will always be detected and corrected.
Option B, symbol bits, is incorrect because symbol bits are not the only type of bit in an MDS code. MDS codes also contain information bits, which are the bits that carry the actual data. The minimum distance of an MDS code is determined by the number of information bits, not the number of symbol bits.
Option C, parity check bits, is incorrect because parity check bits are not the only type of bit in an MDS code. MDS codes also contain information bits, which are the bits that carry the actual data. The minimum distance of an MDS code is determined by the number of information bits, not the number of parity check bits.
Option D, none of the above, is incorrect because the minimum distance of an MDS code is indeed one more than the number of information bits.