Question

Find the synonym of the underlined word.
George Ravencroft's invention of lead crystal in the late $17$th century was crucial to the development of optical lenses.

• A. Essential to
• B. Prior to
• C. Dependent on
• D. Instructive for
• E. Propitious for

Answer 1

The correct option is A Essential to

It is quite evident from the context that crucial means important, necessary, essential. So, for the given sentence, it can be safely stated that George Ravencroft's invention of lead crystal in the 17th century was crucial to or essential to the development of optical lenses. Hence, option A is correct and the others are not because they do not provide the correct answer.