A

Step 1: Determine the quantum numbers for a 3d electron. The quantum number 'n' represents the principal quantum number which is given as 3.
Step 2: The angular momentum quantum number 'l' for a d-orbital is 2. Thus, for 'l' we have 'l = 2'.
Step 3: The magnetic quantum number 'm_l' can take values from -l to +l, hence possible values are -2, -1, 0, +1, +2. Choosing +1 as given in option (A) is valid.
Step 4: The spin quantum number 'm_s' can either be +1/2 or -1/2. For option (A), it is given as -1/2 which is a valid option.
Therefore, the correct quantum numbers for a 3d electron can be represented by option (A).