What will be the output of the following R code?

> x <- list(a = matrix(1:4, 2, 2), b = matrix(1:6, 3, 2))
> lapply(x, function(elt) { elt[,1] })

Which control structure in R is used to execute a block of code repeatedly until a condition is met?

A. if-else loop

B. for loop

C. while loop

D. do-while loop

In R, what is the purpose of the if-else statement?

A. To execute a block of code if a condition is true, otherwise execute another block of code

B. To create a loop that iterates a specified number of times

C. To check multiple conditions sequentially

D. To execute a block of code repeatedly until a condition is met

How is the switch() function used in R?

A. To toggle between TRUE and FALSE values

B. To switch the positions of two elements

C. To select one of several alternatives

D. To change the direction of a loop

In R, what is the syntax for the for loop?

A. for (i in 1:10) { code_block }

B. for (i = 1 to 10) { code_block }

C. for (i = 1; i <= 10; i++) { code_block }

D. for (i from 1 to 10) { code_block }