Задание 26 ЕГЭ, английский язык: Лексико-грамматические навыки

Образуйте от слова POSSIBLE однокоренное слово так, чтобы оно грамматически и лексически соответствовало содержанию текста.

In 1970, some scientists began to question whether Pluto was really a planet. As technology improved the __________________ to see the outer areas of the solar system, they found other objects like Pluto. However, they decided that these did not have enough mass, or quantity of matter, to be considered a planet.