`underset(a)(CH_(3))-underset(b)(CH_(2))-underset(c)(CH_(2))-underset(d)(CH_(2))-F`
Arrange the hydrogens a, b, c, d, in decreasing order of their reactivities towards chlorination:
A. `a gt b gt c gt d`
B. `b gt c gt d gt a`
C. `b gt c gt a gt d`
D. `c gt b gt a gt d`