1. Given the original DNA nucleotide sequence, which of the following is a mutated sequence showing a point mutation? Original: G C A T T A A C G A C A
a. G C T T A A C G A C A U
b. G C A A T A A C G A C A
c. C G T A A T T G C T G T
d. G C C A T T A A C G A C

The correct answer is - b. Original: G C A T T A A C G A C A  

Explanation:

Point mutation is the mutation where change takes place in one of the nucleotides or single base by one of three ways that are insertion, deletion, or substitution of the nucleotide. In insertion, one extra single base is added to the original sequence, In the deletion one of the single base pair is deleted from the single sequence, and in substitution one base is switched with the complementary base.

In all the options, there are more than nucleotide is altered except option B where T is altered with A and cause mutation.

Original sequence: G C A T T A A C G A C A

mutated sequence: G C A A T A A C G A C A

but there is no

i guess you forgot putting it.