Select the most appropriate option that can substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No substitution’.
Prince Charles became a youngest heir to the throne at the age of seven.

Correct option is C

The most appropriate option to substitute the highlighted segment in the given sentence is (c) the youngest heir to the throne.
• Option (c) "the youngest heir to the throne" is grammatically correct.
• It uses the definite article "the" before "throne" to specify the particular throne Prince Charles became the youngest heir to.