The datadir variable value can be seen using . . . . . . . .

Answer: Option A

This question is about finding the value of a specific variable in MySQL called "datadir". This variable stores the location where your MySQL database files are stored.

To find the value of this variable, you use a special MySQL command. The command lets you look at a list of all the variables and their values.

Here's how you find the correct answer:
* Option A: SHOW VARIABLES: This is the correct command used to display the values of all variables.
* Option B: DISP VARIABLES: This is not a valid MySQL command.
* Option C: CONNECT VARIABLES: This isn't a command used for viewing variables.
* Option D: SHOW VARIABLE: This is close, but the correct command requires the plural "VARIABLES".

Therefore, the answer is Option A: SHOW VARIABLES