This question asks which urban planner is credited with first conceptualizing the Linear City model of urban growth. Each of the four names given is linked to a distinct planning idea, so matching the planner to their signature contribution settles the question.
Weighing the four names against their actual planning legacies, only Doxiadis's work centres on organizing a city along a linear axis in the manner the question describes.
Therefore, the correct answer is C.A Doxiadis.