Which of the following sentences contains at least one error?

A$.$ Some people require vary explicit, detailed instruction, while others can deduce what you mean.

B$.$ Despite the mass of data now stored on computer media, many offices still retain hard$-$copy filing systems.

C$.$ Never ignore a client or customer who walks in the door; always acknowledge his or her arrival.

D$.$ When an employee has a problem with another employee, it is best to try to discuss it directly with that person before taking it to a supervisor.