The correct answer is: D. Morpheaform.

Morpheaform, micronodular, and sclerosing are the most aggressive histologic subtypes of basal cell carcinoma (BCC).

Morpheaform BCC:

• Usually found in mid-facial sites
• Waxy, scar-like plaque with indistinct borders
• Wide and deep subclinical extension
• May infiltrate cutaneous nerves (perineural spread)
• Also known as morpheaform or sclerosing BCC

In terms of the variants of basal cell carcinoma (BCC), solid-type isn’t one that is historically described. Superficial and nodular type of BCCs are the least aggressive sub-types.

Superficial BCCs is the most common subtype in the younger age population with a predilection for the trunk and extremities (less commonly seen on the scalp and face). They typically are erythematous macules or thin papules to patches and thin plaques with variable scale, crust and a subtle rolled border edge.

Nodular BCCs are the most common subtype, accounting for nearly 50% of all BCCs. Clinical appearance is notable for a pearly, flesh colored papule with a rolled border edge and arborizing telangiectasias. Predilection for the face especially along the mid-facies: nose, cheeks, nasolabial folds, forehead and eyelids.