According to the passage, which of the following should be encouraged to enhance the learning of math and science 1. Problem solving. 2. Actual research. 3. Repetitive in-class drills. 4. Group work. 5. Rote learning.
A．1 and 3.
B．1, 2 and 4.
C．4 and 5.
D．2, 3 and 5.