To solve the given problem, we will analyze the figure to determine the number of rectangles and triangles and compare these quantities.

First, let's consider the rectangles in the figure:

1. The entire outer figure is a rectangle.
2. There are two smaller rectangles formed by the vertical line dividing the larger rectangle in half.
3. Each half has further subdivisions into rectangles:
   • The top half has one rectangle.
   • The bottom half has one rectangle.

Counting all these, there are 1 (whole) + 2 (side rectangles) = 3 rectangles in the figure.

Next, let's count the triangles:

1. The figure is divided by two diagonals, forming 4 triangles within the larger rectangle.
2. Each diagonal cuts one of the smaller rectangles, forming 2 triangles in each half.

Adding these up, there are 4 (within the whole rectangle) + 2 (top half) + 2 (bottom half) = 8 triangles.

Now let's evaluate the options with these counts:

• Number of rectangles = 3
• Number of triangles = 8

Comparison:

Number of rectangles + 1 = Number of rectangles + 1 = 3 + 1 = 4 < Number of triangles = 8.

Therefore, the statement "Number of rectangles + 1 < Number of triangles." is true.