A. Yes
s + (s + 1/2) + (s + 1/2) + s = 4s + 1
B. no
See above explanation
C. No.
They forgot to add an extra s inside the parenthesis
D. Yes.
2(s) + 2(s + 1/2) = 2s + 2s + 1 = 4s + 1
hope this helps
