In the sentence “Es bueno que ustedes ________ su proyecto de ciencias temprano,” we need the present subjunctive form of the verb, which is used to express wishes, suggestions, or recommendations. The correct form is “hagan” because it matches the subject “ustedes” (you, plural) and agrees with the context of the sentence.
Now let’s analyze the second blank in the sentence “No es cierto que ustedes ________ mucho tiempo con todo lo que se requiere.” Here, we need the indicative form of the verb since it is a statement of fact or denial. The correct form is “tengan” because it matches the subject “ustedes” and agrees with the context of the sentence.
Therefore, the correct option is indeed “a. hagan; tienen.”