Our adventurous explorer, Penelope, is packing her bags! Choose the best way to complete her thought about her upcoming jungle trek.

"If it ___ too much, we will have to take the longer route through the ancient ruins."

The correct answer is rains.

This is a Type 1 conditional sentence, used for real or possible situations in the future. The 'if' clause uses the present simple tense (e.g., "if it rains"), and the main clause uses 'will' + base verb (e.g., "we will have to"). Remember, we don't use "will" in the 'if' clause of a conditional sentence.