Explanation

do-until is not a valid loop structure in C programming.

C provides for, while, and do-while loops for iteration.

Explanation

The conditional operator (? :) is a shorthand for the if-else statement.

It evaluates a condition and returns one value if true, another if false.

Explanation

The format specifier %c is used in scanf to read a single character.

So, km must be a character variable, e.g., char km;.

Explanation

r is the carriage return escape sequence, which moves the cursor to the beginning of the current line.

It does not move to the next line, unlike n (newline).

Explanation

In C, 9 and 4 are integers, so 9 / 4 = 2 (integer division, fractional part is discarded).

Then, 2 * 2 = 4

Explanation

long double provides higher precision than double and float for storing real numbers.

It allows more digits after the decimal point, making it suitable for high-accuracy calculations.

Explanation

math.h is the standard C/C++ header file that contains declarations for common mathematical functions like sqrt(), pow(), sin(), etc.

It must be included when using built-in math operations in programs.

Explanation

The else keyword is used to provide an alternative block of code if the if condition is false.

It works with if to handle two different choices in decision-making.

Explanation

Address consists of text (street, city, etc.).

It is non-numerical.

Marks, bank balance, and roll number are numerical values.

Explanation

A command-line interface is used by DOS systems.

By typing a program's filename at the command prompt, a program can be launched.