Adjective Clause: Indicative or Subjunctive?

Question

Do I use the indicative or subjunctive in these adjective clauses?

Van a dar el premio al científico que logra/logre resolver el problema.

&

Si eres una persona que comprende/comprenda mi situación, llámame.

Answer 1

The first one is something that may (or may not) happen in the future, so it would be in the subjunctive. Will someone resolve the problem?

The second one is in the present following "if", so it's in the indicative.

If you are a person that understands... Si eres una persona que comprende...

But would be subjunctive here (imperfect subjunctive):

If you understood my situation, you could help me. Si comprendieras mi situación, podrías ayudarme.

Answer 2

The use of subjunctive is not always controlled in that many times the choice between subjunctive and indicative depends upon the mood that the speaker wants to create, so in these two phrases either can be used. If you want a nuance of complete, undisputable fact, then indicative can be used. If you want a nuance of "may happen" with the verb in question, then subjunctive can be used.

Answer 3

Thanks, Julian and Tosh! I appreciate you both answering my question.