What major ocean floor feature extends continuously through various oceans and contains a rift valley?

The major ocean floor feature that extends continuously through various oceans and contains a rift valley is the oceanic ridge. It is a significant geological formation characterized by an underwater mountain range, formed by tectonic plates moving apart, allowing magma to rise from the mantle. This process creates new oceanic crust and results in the formation of the rift valley at the crest of the ridge, where the tectonic activity is most pronounced.

In contrast, the abyssal floor refers to the deep ocean floor beyond the continental slope, typically found at depths greater than 3,000 meters, and it is generally flat and featureless. The continental shelf is the submerged area of land that extends from the shoreline of a continent, typically shallow compared to the depths of the ocean, while the continental slope is the steep transition between the continental shelf and the deep ocean floor, marked by a slope that leads to the abyssal plain. None of these features exhibit the continuous, geologically active characteristics of an oceanic ridge, which is why the correct answer is indeed the oceanic ridge.