Just for fun: If you have more than two choices, you could do the following:
library(tidyverse)
df <- tibble(CHOICE = c("car", "bus", "bus", "truck", "car", "bus"))
df %>%
cbind(map_dfc(unique(df$CHOICE), ~tibble(!!.x := .x))) %>%
mutate_at(vars(-CHOICE), function(.x) {.x == .$CHOICE})
Result:
CHOICE car bus truck
1 car TRUE FALSE FALSE
2 bus FALSE TRUE FALSE
3 bus FALSE TRUE FALSE
4 truck FALSE FALSE TRUE
5 car TRUE FALSE FALSE
6 bus FALSE TRUE FALSE