What is (1 + tan α tan β)2 + (tan α – tan β)2 – sec2 α sec2 β equal to?

What is (1 + tan α tan β)2 + (tan α – tan β)2 – sec2 α sec2 �

1.	What is (1 + tan α tan β)2 + (tan α – tan β)2 – sec2 α sec2 β equal to?
A.	0
B.	1
C.	2
D.	4
Answer» B. 1