Match List-I with List-II and select the correct answer:

List-I	List-II
a. Apical cell theory	1. Popham and Chan (1950)
b. Histogen theory	2. Schmidt (1924)
c. Tunica-corpus theory	3. Nageli (1858)
d. Mantle-core hypothesis	4. Hanstein (1868)

A. a-1, b-2, c-3, d-4

B. a-4, b-3, c-1, d-2

C. a-2, b-1, c-4, d-3

D. a-3, b-4, c-2, d-1

Answer: Option D