Some parts of one or more sentences have been jumbled up, and labelled A, B, C and D.
Select the option that gives the correct sequence in which these parts can be rearranged to form a meaningful and grammatically correct sentence.
Their approach sensitized
A. of it. Similarly, behind them, in the halls,
B. flicked on when they came within ten feet
C. a switch somewhere and the nursery light
D. lights went on and off as they left them behind, with a soft automaticity.