A teacher asked her students to design a hot pack. The desired criteria and constraints for the hot pack are as follows: its temperature should remain at or above 90°C for as long as possible
its temperature should remain as constant as possible
it should be durable and leak proof
it should fit inside shoes, gloves, or a pant pocket
The students were instructed to mix calcium chloride crystals in plastic bags filled with water. They were split into three groups, and each group created a design. Each design used a different amount of calcium chloride crystals. The table shows the hot pack designs created by the three groups.

Amount of Time at 90°C (minutes) Variation in Temperature (°C) Durability of Pack (hours) Size of Pack
Design 1 20 0-5 24 10 cm × 6 cm
Design 2 40 0-7 20 10 cm × 6 cm
Design 3 30 0-7 15 8 cm × 5 cm

How could the designs be combined to best meet the criteria and constraints?
A.
time at 90°C of Design 3 and durability of Design 1
B.
time at 90°C of Design 2 and durability of Design 1
C.
temperature variation of Design 3 and size of Design 2
D.
temperature variation of Design 2 and size of Design 3