Both earthquakes and volcanoes are a result of
the sun's energy
plate tectonics
subduction
seafloor spreading

For sure, one of the answers is Plate tectonics. The second answer would most likely be subduction, due to the fact, in the lessons revolving this question, it mentions both earthquakes and volcanoes caused by subduction.

ń, wǒ shuō yīngyǔ, dàn wǒ huì shuō qítā yǔyán, rú xībānyá yǔ fǎyǔ yìdàlì yǔ hé pǔtōnghuà, suǒyǐ bùyào pànduàn, dànshì