An electronic assembly consists of two subsystems $A$ and $B$. Past testing procedures data show that probabilities of failure are $P(A$ fails $)=0.2, P(B$ fails alone $)=0.15$, $P(A \& B$ fail $)=0.15$. Then the probability that $A$ fails alone is equal to

• A

  $0.02$
• B

  $0.03$
• C

  $0.04$
• Correct answer
  D

  $0.05$

Hence, the correct answer is option: 'D'.