Write the following expression as a single summation in terms of k: ∑(m_k² + 5m + 1) for k = 1 to 6.
a) ∑(k² + 5k + 1)
b) ∑(k² + 6k + 1)
c) ∑(k² + 5k + 2)
d) ∑(k² + 6k + 2)