According to Jean Piaget the ability to use symbols for symbols such as letting the letter X stand for an unknown numeral develops during ____________ and enables the children to learn_____________.

Correct option is B

The ability to use symbols for symbols, such as letting the letter X stand for an unknown numeral, develops during the formal operational stage and enables the children to learn algebra and calculus. This stage, which generally begins around age 12 and continues into adulthood, is characterized by the development of abstract thinking and hypothetical-deductive reasoning. During the formal operational stage, individuals can think abstractly, reason logically, and use symbols to represent abstract concepts, allowing them to solve complex problems like those found in algebra and calculus. This represents a significant cognitive leap from the concrete operational stage, where thought processes are more concrete and less abstract.
Information Booster:
(a) During the concrete operational stage (around ages 7 to 12), children develop the ability to think logically about concrete events and understand the concepts of conservation and seriation, but they struggle with abstract concepts like those in algebra and calculus.
(c) Conservation and seriation are indeed key concepts learned during the concrete operational stage, not the formal operational stage.
(d) While the concrete operational stage is crucial for the development of logical thought processes concerning concrete objects and situations, it is not when children typically develop the ability to understand abstract mathematical concepts such as algebra and calculus; this development occurs during the formal operational stage.