Answer: a

Explanation: 

Wouldn’t have is used in conditional sentences, which state conditions. Facebook wouldn’t have decided to use only HTML5 for mobile development IF they’d known how it would work out.

That construction is known as third conditional, for talking about something that didn’t happen that would have made a difference to the current situation. Here are some examples, from Spotlight-Online:

The third conditional or conditional 3 is formed like this:

if + past perfect ,                        would have + past participle

• “What would you have done if it had happened to you?”
• “If I had known you were coming, I would have combed my hair.”
• “I would have invited you to dinner if you‘d called me back.”

* Remember not to put the would have in the if-clause:
• “I would have told you if I would have known the answer.”

It’s not necessary to explicitly say how things would be different:

 
Incorrect: I wish I wouldn’t have sold the farm to buy Facebook stock.
Correct: I wish I hadn’t sold the farm to buy Facebook stock.

Here’s the correct way to use wouldn’t have in a third conditional sentence:

I wouldn’t have sold the farm to buy Facebook stock if I’d known how overpriced it was.
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Answer: b

Explanation: Because would have liked to places the speaker in the past, the present tense is correct. (Source: The Oxford dictionary of American usage and style)

You can put the sentence the other way around, as well. In that case, it would be “I would like to have seen the terms of service before I signed the contract.”