Explanation:

- Blaspheme: This means to speak disrespectfully about sacred things, particularly in a religious context. It's unrelated to mercy killing.

- Altruism: This refers to the selfless concern for the well-being of others. It's about kindness and selflessness, not about ending suffering through death.

- Genocide: This is the deliberate killing of a large group of people, especially those of a particular ethnic group or nation. It involves mass killings, but not with the intention to end suffering painlessly.

- Euthanasia: This is the act of putting someone to death painlessly, especially to relieve suffering from an incurable illness.

- Correct Answer: Euthanasia