This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
Which of the following is the most common form of malignant melanoma? 
Select and explain. 
A. Nodular, B. Superficial spreading, C. Acral lentiginous, D. Mucosal
B: Superficial spreading
Answer: B: Superficial spreading 
Explanation: The commonest type of melanoma is the superficial spreading melanoma (SSM). The melanoma progress through 3 phases: in situ, radial growth, veical growth. NB: A primary melanoma with no recognizable adjacent in situ or radial growth phase is nodular melanoma. Melanoma with similar prevalence in all ethnic groups- acral lentiginous Ref: Rook's textbook of dermatology, Edition-8, Page-54.45.