My guess is that you forgot to fully separate the answers. so assuming this is multiple choice i'm going with A
Experimental design means planning a set of procedures to investigate a relationship between variables. To design a controlled experiment, you need: A testable hypothesis. At least one independent variable that can be precisely manipulated. At least one dependent variable that can be precisely measured
The relationship between natural selection and evolution would best be described from the phrase, "natural selection leads to evolution." As species change through the process of natural selection this leads to an evolution of the species.