Practice question

The right choice is C: Serine/threonine kinase. In Phototropin+All, that matches how the process or concept actually works — the other choices mix up related ideas or use the wrong mechanism. Skip these: A) Tyrosine kinase; B) Histidine kinase; D) MAP kinase. A quick check: if an option needs energy, pumps, or the opposite direction of movement, ask whether that really applies.