Answer:
d. ns2np3
Explanation:
In the first main group all elements have a singly occupied s orbital.
In the second main group, all elements have a doubly occupied s orbital.
In the third main group or 13th group all elements have a doubly occupied s orbital and a singly occupied p orbital.
In the fourth main group or 14th group all elements have a doubly occupied s orbital and a doubly occupied p orbital.
In the fifth main group or 15th group all elements have a doubly occupied s orbital and a triply occupied p orbital.
And so on.
