Not entirely sure how to do these. Can someone walk me through please? The answers are D, E and A if that helps.

Consider the following charcteristic table for a priority encoder: a b c dI E F G 0 0 0 00 X X 0 0 0 1 1 0 0 0 0 1 X1 0 1 0 1 X X 1 1 0 1 X X X 1 11 Function E indicates whether the result is valid or not, Function F produces the most significant bit of the two-bit result, and function G produces the least significant bit of the two-bit result. 05. Consider the circuit described in Figure 1. Which of the following is the optimal expression for function E? A) B) C) D) E) E(a,b,c,d)=a,b,c,d, E(a,b,c,d) = a + a,,b + a,b,d E(a,b,c,d) = b + ab' + b,c E(a,b,c,d) = a + b + c + d None of the above 06. Consider the circuit described in Figure 1 Which of the following is the optimal expression for function F? A) B) C) D) F(a,b,c,d) F(a,b,c,d) F(a,b,c,d) F(a,b,c,d) None of the a + c =a+a,b =b+ab, = d, + ad above. + bd 07. Consider the circuit described in Figure 1. Which of the following is the optimal expression for function G? A) B) C) D) E) G(a,b,c,d)=a+b,c G(a,b,c,d)=a+a,,b,c G(a,b,c,d) ab + ab' + G(a,b,c,d) ab + b, c + None of the above. ab' c' a,b,c