What does it mean by least complex to most complex?

Microorganisms are involved in each of the following processes excepta. smog production.b. food production.c. infection.d. o2 production.e. decomposition of organic material.

My question says on my assignment. read the following scenarios and decide which of the properties of life are being described. the first one is. katherine stopped on the way to school to grab some donuts. 2. because a dog cannot sweat, it has to pant in order to stay cool. 3. an elephant trun had no bone but 4,000 muscles. i have no idea what i am supposed to anwer. i can't find the answer in my notes or book that i can understand anyway

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.