Inhabit means a place or environment to live in for a person or animal or a group.

Vacate, move and reside means to leave a place and are opposite to live. Reside is the only word most nearly means as inhabit.

The given number series is 2, 3, 7, 16, 32, ?

$$\begin{gathered} 2 \\ 2 + 12 = 3 \\ 3 + 22 = 7 \\ 7 + 32 = 16 \\ 16 + 42 = 32 \\ 32 + 52 = 57 \\ \end{gathered}$$

Hence, the next number in the given number series is 57.

South Africa hosted the 10th edition of BRICS Summit 2018 in Johannesburg on July 25. 

Sober means not afected by alcohol, clear headed, very serious, sensible,...

Antonyms of Sober are :: light hearted, frivolous, sensational, emotional,...

The relative pronoun acts as the subject or object of the relative clause. It replaces words like she, he, him, her, they, them etc.

It is, therefore, wrong to repeat the pronoun in the relative clause.

Hence, the correct sentence is Shreya, who is my best friend, is a singer.

Relegate means Assigning an inferior rank or position to. That means, downgrading or pulling down, lower a person.

All other options have words with opposite in meaning.

Hence, Relegate is an English word which is similar in meaning to Downgrade.

The Ministry of Women and Child Development has launched #Childline1098 childline contest to spread awareness on human trafficking. 

Human trafficking is the trade of humans for the purpose of forced labour, sexual slavery, or commercial sexual exploitation for the trafficker or others.

The WCD Ministry has invited people to share images of the logo of Childline 1098, the nationwide emergency helpline for children in distress, that they spot at unique locations and send it with a tagline to win a cash price, in a bid to spread awareness on trafficking.

The contest has been organised to mark 'World Day against Trafficking in Persons' on July 30.

The Childline has been operating at 450 locations, including 76 key railway stations, across the country.