Which of the following list of numbers forms an arithmetic progression?

(A) 1, -1,-3 -5, .......

(B) -1.2, -3.2, -5.2, -7.2, ...........

(C) -2, 2, -2, 2, -2, ........

(D) 2, $\frac{5}{2}$, 3, $\frac{7}{2}$ ......

Choose the correct answer from the options given below:

An arithmetic progression is a sequence where the difference between any two consecutive terms is constant. This constant is called the common difference $d$.

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Checking option (A): 1, -1, -3, -5, .......

$-1 - 1 = -2$

$-3 - (-1) = -2$

$-5 - (-3) = -2$

The common difference is $-2$ (constant).

This is an arithmetic progression.

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Checking option (B): -1.2, -3.2, -5.2, -7.2, ...........

$-3.2 - (-1.2) = -2$

$-5.2 - (-3.2) = -2$

$-7.2 - (-5.2) = -2$

The common difference is $-2$ (constant).

This is an arithmetic progression.

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Checking option (C): -2, 2, -2, 2, -2, ........

$2 - (-2) = 4$

$-2 - 2 = -4$

$2 - (-2) = 4$

The differences alternate between $4$ and $-4$.

This is not an arithmetic progression.

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Checking option (D): 2, $\frac{5}{2}$, 3, $\frac{7}{2}$ ......

Converting to fractions: $\frac{4}{2}$, $\frac{5}{2}$, $\frac{6}{2}$, $\frac{7}{2}$

$\frac{5}{2} - \frac{4}{2} = \frac{1}{2}$

$\frac{6}{2} - \frac{5}{2} = \frac{1}{2}$

$\frac{7}{2} - \frac{6}{2} = \frac{1}{2}$

The common difference is $\frac{1}{2}$ (constant).

This is an arithmetic progression.

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Options (A), (B), and (D) form arithmetic progressions.