Non$-$Euclidean geometry, which challenged Euclid's parallel postulate, was developed in the $19$th century by mathematicians like:

$($a$)$ Carl Friedrich Gauss and Nikolai Lobachevsky

$($b$)$ Leonhard Euler and Joseph$-$Louis Lagrange

$($c$)$ Blaise Pascal and Pierre de Fermat

$($d$)$ Isaac Newton and Gottfried Wilhelm Leibniz????