Let's hack the argument.
Question stem type: Strengthening some part of the argument. Note: First, look at the question stem but its structure not its meaning. If you look at the meaning, you loose your attention by thinking over and over the question while reading.
First sentence: Many television viewers own videocassette recorders (VCR’s). ---> Background info.
Companies that advertise on television complain that VCR ownership hurts their business, since a VCR makes it possible to view television programs without watching the commercials. --> Evidence and its proof.
Indeed, two-thirds of those who tape programs on a VCR edit out the commercials when viewing the programs.--> another proof which supports the evidence. (2/3 is used. So we may relate to numbers in explaining the right answer. )
Which of the following, if true, would most strengthen the companies’ complaint that VCR ownership is currently hurting their business?---> Question says to support the evidence. So, if any answer below explains something new relevant to the argument, it is the right answer.
(A) The methods for determining audience size, which in turn determines charges for advertising time, count households that are merely recording a program as households that are watching it.---> It conveys that people are watching what they record. It support the main proof. So this may be right. We should look at other answers.
(B) VCR manufacturers who advertise on television would themselves suffer the damage, if any, to advertisers’ interests that is caused by VCR’s.---> reexplains the argument in a general condition deeply. We don't need to reexplain the argument, but we should explain the main proof to most strengthen the evidence. Hence, OUT.
(C) There are VCR’s that are in the early stages of development that will automatically edit out commercials during the recording process.---> I, myself, got trapped into this guy without noticing 'will'. We don't care for future as we are talking about the present proccess. Hence, OUT.
(D) Those who tape programs on VCR’s, but who do not edit out commercials when viewing the programs, tape more often than those who do edit out the commercials.------> This may weaken the evidence rather than strengthen. So, OUT.
(E) Some television commercials are as entertaining or informative as the programs they interrupt.---> This is general and irrelevant to the topic. So, OUT.
So, The right answer is A