Questions

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.

From the given data,

1 rabbit is going towards river not the six eephants. And these 6 elephants saw 2 monkeys are going towards river. Each monkey is holding 1 tortoice.

Hence, number of animals going towards river are 1 rabbit, 2 monkeys and 2 tortoice

= 1 + 2 + 2

= 5.

Godavari, India's second longest river after the river Ganga and is one among the peninsular rivers.

The river Godavari is often referred to as Vridha Ganga because of its large size and extent among the peninsular rivers.

90 D in a R A => 90 degrees in a Right Angle. 

This is similar to 

26 L of the A = 26 Letters of the Alphabet

12 S of the Z.