You plan to use an RDD framework to measure the impact of some policy intervention. You first

draw a scatter plot of the outcome variable against a running variable. The plot appears to be complex with no definite linear or quadratic trend. Which is the most appropriate approach in this case $-$

a$.$ Use all data points and run a higher$-$order $($greater than $4)$ polynomial RDD$.$

b$.$ Select a bandwidth and run a linear polynomial RDD$.$

c$.$ Select a bandwidth and run a higher$-$order $($greater than $4)$ polynomial RDD$.$

d$.$ Use all data points and run a linear polynomial RDD