Choose the correct option from the following:
June is too short to get hold of that branch all by _______.

The correct answer is: Herself

The reflexive pronouns sometimes suggest doing something 'alone'. In such cases, they are complemented with 'by'.
June is too short to get hold of that branch all by herself.
Here, the correct option is 'herself'. It suggests June is too short to get hold of a branch alone, without any help.