ratio of 5ᵗʰ term from the beginning and fifth term from the end in the binomial expansion of (2¹⁄³ 1/2(2)/¹⁄³)¹⁰ is
a. 1:2(6)¹⁄³
b. 2(36)¹⁄³:1
c. 4(36)¹⁄³:1
d. 1:4(16)¹⁄³