Use induction to prove that for any integer n≥1,∑j=1n​(2j+1)=n(n+2). What is being proven in the base case?
a. ∑⁰j=1​(2j+1)=0
b. ∑¹j=1(2j+1)=1⋅(1+2)
c. ∑ʰj=1 (2j+1)= n(n+2)
d. ∑ᵏj=1​(2j+1)k=(k+2)
e. None of these