Which of the following statements is (are) true about free radical halogenation of alkanes?
A The first of the chain-propagating steps is rate-determining.
B The reaction proceeds by way of a flat $sp^2$ hybridized free radical.
C The chain-initiating step involves cleavage of a carbon-hydrogen bond to afford a carbon radical and a hydrogen atom.
D Statements (The first of the chain-propagating steps is rate-determining) and (The reaction proceeds by way of a flat $sp^2$ hybridized free radical) are both true.