Final answer:
To express the size of the giant dragonfly as a percentage of the size of the modern dragonfly, divide the size of the giant dragonfly by the size of the modern dragonfly and multiply by 100%.
Step-by-step explanation:
To express the size of the giant dragonfly as a percentage of the size of the modern dragonfly, we can use the formula:
Percentage = (Size of Giant Dragonfly / Size of Modern Dragonfly) x 100%
Let's say the size of the giant dragonfly is 5 cm and the size of the modern dragonfly is 10 cm. Plugging in these values into the formula, we get:
Percentage = (5 cm / 10 cm) x 100% = 50%
Therefore, the correct answer is a) 50%.