Answer
neither
Work Step by Step
In order for a sequence to be geometric, the quotient of all consecutive terms must be constant.
Hence here: $3/4-2/3\ne4/5-3/4$, which is not constant thus it is not a geometric sequence.
In order for a sequence to be arithmetic, the difference of all consecutive terms must be constant.
Hence here: $\frac{\frac{4}{5}}{\frac{3}{4}}\ne\frac{\frac{3}{4}}{\frac{2}{3}}$, which is not constant thus it is not an arithmetic sequence.
Hence it is neither.