Please experts give me a trick to solve these types and questions

Dear student,

For such questions you will have to draw the punnett square. 

	AB	Ab	aB	ab
AB	AABB	AABb	AaBB	AaBb
Ab	AABb	AAbb	AaBb	Aabb
aB	AaBB	AaBb	aaBB	aaBb
ab	AaBb	Aabb	aaBb	aabb

Thus there are 16 possible progeny in this cross. 
Out of these chance of getting the progeny Aabb is 2/16 thus correct answer is 1/8 option - 2

Regards