You have to install a new module on the production environment. All the module is adding a new product attribute. You enabled maintenance mode, copied the module code, run bin/magento setup:upgrade and disabled maintenance mode.
A. It will clean all caches which will cause a performance degradation
B. The new attribute will be invisible on the storefront until the cache is cleaned manually
C. It will void all active sessions
D. It will clean static assets from the pub/static folder