What does a controlled experiment work with?

What are two examples of conduction that we use everyday

Describe how a non-resistant staphylococcus aureus bacterium can produce a bacterium that is resistant to methicillin

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred