Option 1 -> The passage explicitly states that "engaging in leisure activities can improve health" and help protect against various diseases, connecting them to stress reduction.
Option 2 -> "Passive" refers to a type of focus characteristic in relaxed brain states, not a category of activities.
Option 3 -> "Multiple" appears in the passage referring to studies ("meta-analysis of multiple studies"), not types of activities.
Option 4 -> "Antidote" is used as a noun to describe what hobbies are ("hobbies are a powerful antidote to stress"), not as an adjective modifying activities.
Hence, Option 1: leisure -> The passage directly mentions that leisure activities improve health and protect against stress-related conditions, making them function like medicine to alleviate stress -> correct