A) TNAVERSBO | B) TNAVRESBO |

C) NTAVERSBO | D) VANTRESBO |

Explanation:

Given word is O B S E R V A N T. After making the change as given in the question, we get the following arrangement:

T N A V R E S B O.

A) A | B) B |

C) C | D) D |

Explanation:

6-3 = 3 9-4 = 5 (3x5=15) 15=O

7-2 = 5 7-3 = 4 (5x4=20) 20=T

9-6 = 3 5-1 = 4 (3x4=12) 12=L

Similarly, 4-1 = 3 8-5 = 1 (3x1=3) 3=C

A) E | B) Z |

C) X | D) F |

Explanation:

first letter A with last letter Z

similarly 2nd last letter Y with 2nd letter B

Now 3rd letter C with 3rd last letter X

4th last letter W with 4th letter D

and so on....

Therefore the missing letter is X

A) UJI | B) VIJ |

C) XLM | D) DOP |

Explanation:

First letter series S,T,U,V

second and third letter series CD,EF,GH,IJ...

so answer = VIJ

A) VPCFT | B) DHLRX |

C) CFKNT | D) None |

Explanation:

The logic behind the sequence given in the question is +4, +4, +6, +6

Therefore, the sequence which follows the same logic in the given options is DHLRX.

A) S | B) I |

C) J | D) T |

Explanation:

Here the series has mixed two series.

n m l k...! reverse alphabet

o p q r ...! forward alphabet

So the letter before k is j and after that letter after r is s and so on...