Question

9 in what manner do scientists gain knowledge about experimental materials and procedures?
trial and error
random selection
conducting background research
asking colleagues

Explanation:

Scientists typically conduct background research to gain knowledge about experimental materials and procedures. Background research includes reading scientific literature, previous studies related to the experiment, which provides a comprehensive understanding of what has been done before, the available materials, and the standard - or improved - procedures. Trial and error is more about the process of experimentation itself, random selection is a method for sample selection in some cases, and asking colleagues is a secondary or supplementary approach.

Answer:

Conducting background research