The first sentence is generally considered correct.
A suggested B [verb in root form]....
Regarding that, here is an extract from a Wikipedia article about grammatical mood:
The subjunctive mood, sometimes called conjunctive mood, has several uses in dependent clauses. Examples include discussing imaginary or hypothetical events and situations, expressing opinions or emotions, or making polite requests.
A subjunctive mood exists in English, though it is used in English much less than in many other Indo-European languages. In English, this mood has, for some uses, become something of a linguistic fossil. An example of the subjunctive mood is "I suggest that Paul eat an apple". In this instance, Paul is not in fact eating an apple. The sentence merely presents the hypothetical (but unfulfilled) actions of Paul according to the speaker's suggestion."
You can read more about the subjunctive mood here.
Note: Though this is how the tense should be chosen, in some situation some people may prefer using past tense. Read more about it in Peter's answer.
This is the wrong way to analyze it. (Thanks, Peter, for pointing it out!)
There is debate over this among grammarians that goes back as far as the 18th century. To sum up, there are mainly two different views as to the rules governing the sequence of tenses in a sentence.
- Natural sequence of tenses: The tense of a verb in a subordinate clause is not determined by the tense of the verb in
the superordinate clause, but is determined simply according to the
sense of the clause taken apart from the rest of the sentence. Just imagine yourself at the point in time denoted by the main verb, and use the tense for the subordinate verb that you would have used at that time.
In this sense the first sentence is correct. You had not yet gone to Kazakhstan when the suggestion was made.
- Attracted sequence of tenses: The tense of a verb in a subordinate clause is determined by the tense of the verb in the superordinate clause. If the main verb of a sentence is in the past tense, then other verbs must also express a past
viewpoint, except when a general truth is being expressed.
But in this sense the second sentence should be considered correct. And that is probably also why it is this view, and the problems that it causes, that has generated the most discussion amongst grammarians (according to Merriam-Webster).
I personally would prefer the natural sequence of tenses and go with the first sentence.