30. According to the crystal field theory, is a low-spin or high-spin complex cation? How many unpaired d-electrons are expected for it? (A) low-spin, 0 unpaired electron (B) low-spin, 1 unpaired electron (C) low-spin, 3 unpaired electrons (D) high-spin, 3 unpaired electrons (E) high-spin, 5 unpaired electrons