The reason Democratic nominee Woodrow Wilson won the presidential election of 1912 is that Taft and Roosevelt split the Republican vote. Option B is correct.
The United States presidential election of 1912 was the 32nd quadrennial presidential election, held on Tuesday, November 5, 1912. In that presidential elections, Roosevelt won 88 electoral votes, while Taft carried just two states, taking 8 electoral votes. Democratic Governor Woodrow Wilson of New Jersey unseated incumbent Republican President William Howard Taft and claimed victory over former President Theodore Roosevelt.