What needs to be added to the code to create a new RDD with the number of words in each line of the file?

rdd $=$ sc$.$textFile$("$file$.$txt$")$

new$\_$rdd $=$ rdd$.\_\_\_\_\_($lambda x: len$($x$.$split$()))$

A$.$

filter$()$

B$.$

reduce$()$

C$.$

flatMap$()$

D$.$

map$()$