A large room has three entrances. A light switch is to be placed by each entrance. Each switch should be able to reverse the condition of the lights (i. e. turn the lights on or off when entering or leaving). The 3 light switches are indicated as A, B and C and are considered to be true when the switch is up. The light is considered to turn on when it is true or high. The light is initially off when all three switches are off (down). In terms of the 3 variables, the simplest expression for L, of those given, isp 1. A'(BC'+B'C)+A(BC'+B'C)'
2. no other answer is correct
3. AB+AC+BC
4. A+B+C
5. AB'C' + A'BC' + A'B'C