(1)C, the sum of the two adjacent angles of the parallelogram is 180 degrees, the sum of the two adjacent angles after being bisected by the bisector is 90 degrees, and the sum of the internal angles of the triangle is 180 degrees, so the third triangle is a right angle.

(2)D, if the quadrilateral is a parallelogram, then its diagonal must be equally divided, so A is a rectangle or isosceles trapezoid or irregular figure, B is a diamond or special isosceles trapezoid or irregular figure, C is a square or irregular figure, and D must be a diamond.

(3) 1.5 yuan, assuming that eggs, duck eggs and goose eggs are each X, Y, Z, then 13x+5y+9z = 12.7, 2x+4y+3z = 4.7.

Simplified Y=0.2+X, Z= 1.3-2X, then X+Y+Z= 1.5.

(4) The shortest distance is 150 decimeter, because we know from the topic that ants crawl spirally, and A and B are on the same side, so the climbing distance is a spiral circle, which is an integer multiple of the circumference. The shortest distance is a circle, and the length of the circle is 150 decimeter, which is greater than the height of the bucket, so ants can climb to the top of the bucket in one circle.