For Mohs micrographic surgery, CPT® coding is based on the anatomic location of the lesion, the number of stages, and the number of tissue blocks per stage.

17311: This code is used for Mohs surgery on body areas such as the trunk, arms, or legs for the first stage.

17315: This is an add-on code used when more than five tissue blocks are examined in a single stage. Since this case involved six tissue blocks, 17315 is appropriate.

Explanation of incorrect answers:

A. 17313, 17314, 17315: Incorrect, as 17313 applies to the head, neck, hands, feet, or genitalia, not the arm.

C. 17313, 17315: Incorrect, as 17313 is not appropriate for the arm.

D. 17311, 17312, 17315: 17312 is used for additional stages beyond the first, which is not applicable here since only one stage was performed.

E. 85B2-335 is not a valid CPT code for Mohs surgery.

Thus, the correct answer is B. 17311, 17315, which accurately reflects a single-stage Mohs surgery with six tissue blocks on the arm.