The experimental variable to be changed in this study is light intensity, which will be divided into three levels: low, medium, and high. The type of plant seeds utilized, the soil type, the frequency of watering, and the ambient temperature are all variables that must be kept consistent. what are credible sources and Background/justification

a) Interviews with experts in the field
b) Peer-reviewed scientific journals
c) Wikipedia articles
d) Personal blogs and websites