Consider the following commands in R: x1 <- 6:3, x2 <- c(2,4,6,8). What is the output of x1 - x2?
1) [1] -1 -1 -1 -1
2) [1] -1 0 -1 -2
3) [1] 4 1 -2 -5
4) [1] 4 1 0 -3