This word means the same as the given italicized word. Hence option B is correct.
Option A: 'Primary' means 'of chief importance, principal'.
Option C: 'Opening' means 'a space or gap that allows passage or access'.
Option D: 'Girlish' means 'of or characteristic of a girl'.
These words do not mean the same as the given word 'maiden'.
So, options A, C and D are wrong.