Seven people Anuj, Akash, Bablu, Dharmendra, Ritu, Sudha and Ranjan are standing in a single line, facing a house. Ritu is somewhere ahead of Sudha. There is exactly one person standing between Bablu and Ranjan. Dharmendra is immediate behind of Anuj. Sudha is behind both Akash and Dharmendra. If Dharmendra and Bablu are fourth and fifth in line respectively, then which of the following must be true?

Given information:

• Seven people in a line facing a house
• Dharmendra is 4th in line
• Bablu is 5th in line

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Since Dharmendra is immediately behind Anuj and Dharmendra is at position 4:

Position 3: Anuj

Position 4: Dharmendra

Position 5: Bablu

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There is exactly one person between Bablu and Ranjan.

Bablu is at position 5, so Ranjan could be at:

• Position 3 (with position 4 between them) - but position 3 is occupied by Anuj
• Position 7 (with position 6 between them) ✓

Position 7: Ranjan

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Sudha is behind both Akash and Dharmendra.

Dharmendra is at position 4, so Sudha must be at position 5, 6, or 7.

• Position 5 is Bablu
• Position 7 is Ranjan
• Therefore, Sudha must be at position 6

Position 6: Sudha

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Remaining people: Akash and Ritu

Remaining positions: 1 and 2

Ritu is ahead of Sudha (position 6), so Ritu can be at position 1 or 2. ✓

Sudha is behind Akash, so Akash can be at position 1 or 2. ✓

Both constraints are satisfied regardless of whether:

• Akash is 1st and Ritu is 2nd, OR
• Ritu is 1st and Akash is 2nd

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In both possible arrangements, Sudha is at position 6.

Therefore, Option 3 (Sudha is sixth) must be true.