Answer: (i) Not occurring of backtracking

Explanation

• Left factoring is a grammar transformation that factors out the common prefix of two or more production alternatives.
• It is used to remove uncertainty about which alternative to choose when a common prefix could lead to two different nonterminal, which otherwise forces the parser to backtrack while building a predictive (LL) parser.

How it works:
$$A \to \alpha\beta_1 \mid \alpha\beta_2 \;\Rightarrow\; A \to \alpha A', \quad A' \to \beta_1 \mid \beta_2$$

In an LL(1) (predictive top-down) parser the decision is made by looking at the first token; factoring out a common prefix ensures the choice is deterministic, so backtracking never occurs.

Hence left factoring guarantees:
$$\boxed{\text{(i) Not occurring of backtracking}}$$