Are students able to leave MC question open after answering?

a_a_m_tuerlings
Community Explorer

I am struggling with the Canvas Quizzes and applying a guessing correction. Normally we test on paper and ask our students to leave a MC question open when they do not know the answer (for calculation of the guessing correction). I see that in Canvas students can skip a question if they do not want to answer. However, once a student has clicked one of the answers it does not seem possible to leave the question open anymore. Students are then forced to choose between the options. 

Is there a possibility that students can remove their answer on an MC question after they have initially chosen one of the options? 

Aniek Tuerlings