A letter series is given below in which some letter are missing. Select the  option that gives the letters that can fill these blanks in that order.
a_ca_bab_ad_abc_db

Direction: In these questions the symbols $ , @ , £ , • and # are used with different meanings as given below :
' X $ Y ' means X is neither greater than nor smaller than Y '
 ' X @ Y ' means X is neither greater than nor equal to Y '
 ' X £ Y ' means X is neither smaller than nor equal to Y '
 ' X• Y ' means X is not smaller than Y '
' X # Y ' means X is not greater than Y '
( A ) If only conclusion I is true
( B ) If only conclusion II is true
( C ) If either conclusion I or II is true
(D ) If neither conclusion I nor II is true
( E ) If both conclusion I and II are true    

Statements:
No curtain is an element.
All elements are pillows.
Conclusions:
I. All pillows being curtains is a possibility.
II. Some elements are definitely not curtains.

In each of the following questions, which one of the four interchanges in signs and numbers would make the given equation correct?
( 3÷4 ) + 2=2 

Which answer figure will complete the pattern in the question figure?

Find the minimum number of straight lines required to make the given figure.

Find out which of the figures (1), (2), (3) and (4) can be formed from the pieces given in figure (X).