7 + 7 + 7 + 7 + 7 means 7 is added 5 times
It could be written as
5(7)
7 x 5 and
7 . 5
But it can not be written as 7^5 because 7^5 means 7 x 7 x 7 x 7 x 7
Hence, 7^5 does not represent the expression 7 + 7 + 7 + 7 + 7
This makes the correct option to be the third option. That is 7^5