Consider the following student relation.

Student relation has Name, Subject1_Marks, and Subject2_Marks attributes.

Name	Subject1_Marks	Subject2_Marks
A	10	5
B	Null	10
C	20	15
D	Null	20
E	30	Null
F	Null	25

What is the output for the given SQL query?

Query:

Select count(Subject1_Marks)

From student;