This is a normal nucleotide sequence found on a section of DNA:

A-A-T-A-G-C-A-T-T
What is a small-scale mutation caused by deletion?
A) A-A-T-A-C-A-T-T
B) A-A-T-A-G-C-A-T-A
C) A-A-T-A-C-G-A-T-A
D) A-A-U-A-G-C-A-U
I think the answer is a!

A is correct.

To determine the correct answer, we need to understand what a small-scale mutation caused by deletion entails. A deletion mutation occurs when one or more nucleotides are removed from a DNA sequence.

Comparing the original sequence "A-A-T-A-G-C-A-T-T" to each option, we can identify which one represents a deletion mutation.

Option A) A-A-T-A-C-A-T-T: In this sequence, the nucleotide "G" has been deleted, which matches the description of a deletion mutation.

Option B) A-A-T-A-G-C-A-T-A: No deletion has occurred here, as the original sequence remains intact.

Option C) A-A-T-A-C-G-A-T-A: In this sequence, the nucleotide "G" has been replaced with a "C" rather than deleted.

Option D) A-A-U-A-G-C-A-U: This sequence includes a different type of mutation altogether, as the nucleotide "U" (uracil) is present. It does not represent a deletion mutation.

Therefore, the correct answer is A) A-A-T-A-C-A-T-T, as it shows a small-scale mutation caused by deletion.