What factor can cause infectious diseases but cannot cause noninfectious diseases? • environment
• genetics
• lifestyle
• Protozoa

It think it has to do with genetics and the environment

Explanation:

how to know you're in love with someone you've just started getting to know can be a bit tricky because — feelings aside — they are technically still a stranger to you. although you might feel the urge to dive in and start professing your undying love for them asap, it's important to remember that it can be easy to confuse feelings of immense attraction with actual love.

theres nothing above