In the C programming language, several basic data types are available, each with a typical storage size. On most common implementations, which of the following standard C data types usually has the least storage size in bytes?

Introduction / Context:
This question examines your knowledge of basic C language data types and how much memory they typically occupy. While exact sizes can vary between systems, the relative ordering is fairly consistent in most common implementations used in teaching and in industry. Understanding which type uses the least storage is important when working close to the hardware, optimizing memory usage, or interfacing with binary file formats and communication protocols.

Given Data / Assumptions:
The question asks which C data type has the least storage requirement among char, double, int, and float. We assume a typical modern system where char is one byte, int is at least two or four bytes, float is commonly four bytes, and double is commonly eight bytes. The C standard allows some variation, but it guarantees that sizeof(char) is one and that sizeof(double) is at least as large as sizeof(float) and sizeof(int). The question expects the basic, widely taught configuration rather than exotic hardware.

Concept / Approach:
In C, the char type is used to represent single characters and small integers. The standard defines sizeof(char) as one byte, which is the smallest addressable unit of memory on most systems. The int type is usually implemented as at least two bytes, and often four bytes, to efficiently represent typical integer ranges. The float type is a single precision floating point value and is usually four bytes, while double is double precision and typically eight bytes. Based on these relationships, char clearly has the smallest storage requirement among the options listed.

Step-by-Step Solution:
Step 1: Recall that the C standard guarantees that sizeof(char) equals one byte.Step 2: Remember that int, float, and double are all designed to represent larger ranges or more precision than char and therefore use more bytes.Step 3: Compare typical sizes: char as one byte, int as at least two or four bytes, float as four bytes, and double as eight bytes.Step 4: Conclude that char is the data type with the least storage among the given options.

Verification / Alternative check:
You can write a simple C program that prints the result of sizeof for each type to confirm this behavior on a specific system. For example, code that prints sizeof(char), sizeof(int), sizeof(float), and sizeof(double) will usually show values like 1, 4, 4, and 8 respectively. Even on systems where int might be two bytes, char remains the smallest. This experimental verification aligns with textbook explanations and standard teaching examples in C programming courses.

Why Other Options Are Wrong:
Option B is wrong because double is a double precision floating type and is intentionally larger than float to provide more precision and range. Option C is wrong because int is used for general integer arithmetic and therefore uses more bytes than char. Option D is wrong because float is a single precision floating type that typically requires more storage than an 8 bit char. Only option A correctly identifies char as the data type with the least storage among the given choices.

Common Pitfalls:
Some learners incorrectly assume that int must always be the smallest useful type because it is so commonly used. Others mistakenly think that the exact sizes are fixed by the language standard rather than implementation dependent, leading to confusion. It is also easy to forget that char is defined as the smallest addressable unit and is not just for characters but also for small numeric values. Always remember the general rule that char is smallest, followed by int and float, with double usually being the largest among these basic types.

Final Answer:
The correct answer is char data type used to store single characters.