Final answer:
Attempting to convert non-numeric character strings 'a', 'b', 'c' to numeric values using as.numeric(x) in R will result in NAs and a warning message, hence the correct answer is A) An error. This 'error' in R refers to a warning rather than a full stop error.
Step-by-step explanation:
When you attempt to convert a character vector to numeric values in R using the as.numeric function, the function will try to interpret the character strings as numbers. If the character strings are not valid numbers (as is the case with characters 'a', 'b', 'c'), the function will return NA and throw a warning message about the introduction of NAs by coercion.
In the given example, with x <- c("a", "b", "c"), calling as.numeric(x) will not give desirable numeric values or corresponding numbers for the alphabets. Instead, it leads to a conversion of each character to NA. Thus, the correct option is:
A) An error.
This error is not the conventional stop error where the function would not execute, but a runtime warning indicating that the provided data cannot be coerced into numeric values accurately.
Here is a code snippet:
R> x <- c("a", "b", "c")
R> as.numeric(x)
[1] NA NA NA
Warning message:
NAs introduced by coercion
This output clearly shows that the function triggers a warning and returns a vector of NAs.
Please note that while the prompt says 'return an error', in R terminology this usually implies a warning which still results in a return value but with 'NA' for non-convertible characters.