帮我讲解这道高中数学题目---**Question Stem:** (2025春•安徽月考) 如图, △O'A'B'是水平放置的△OAB用斜二测画法画出的直观图, 其中O'A'=O'B'=2, 则△OAB的面积是 ( ) **Options:** A. 1 B. 2 C. 4 D. 8 **Chart/Diagram Description:** * **Type:** Geometric figure illustrating a triangle and coordinate axes, representing an oblique projection (斜二测画法 - oblique drawing method). * **Main Elements:** * **Coordinate Axes:** Two axes labeled x' and y'. The x'-axis is horizontal, extending to the right with an arrow. The y'-axis is inclined upwards to the left from the origin O', extending upwards with an arrow. * **Origin:** Point O' is the origin, located at the intersection of the x' and y' axes. * **Points:** Points A' and B' are vertices of the triangle O'A'B'. A' is on the positive x'-axis to the right of O'. B' is in the upper left region relative to O'. * **Triangle:** Triangle O'A'B' is formed by connecting points O', A', and B'. * **Lines:** Lines segment O'A' is along the x'-axis. Line segment O'B' is along the y'-axis. Line segment A'B' connects A' and B'. **Other Relevant Text/Information:** * The figure shows the oblique projection of a horizontally placed triangle △OAB, resulting in the triangle △O'A'B'. * The oblique drawing method (斜二测画法) is used. * Given lengths in the oblique projection: O'A' = O'B' = 2. * The question asks for the area of the original triangle △OAB.