Red has a longer wavelength than yellow
An extensive property is a property of a substance that is dependent on the size or the amount of the substance in a system. Examples are number of moles, volume, energy, entropy, heat capacity, internal energy and mass. This would also be the same definition for extensive values. From the problem statement, the extensive values are the cost and price. These values have units of $ per gram which, obviously, dependent with the mass of the gasoline. The other values like the humidity, air pressure and the hardness are called intensive values since they are independent of the amount of the substance.
The true option is a) they form a 90 degree angle.
Pythagorean theorem is valid for right triangles, which is what you can form when the two vectors have a 90 degree angle.
Regarding the other options:
b) They are equal in magnitude: this is not a condition because Pythagoream theorem is valid for any magnitude as long as the angle is 90°C.
c) They have the sam directions: false, because if the two vectors have the same directions the magnitud is the sum of the two magnitudes.
d) They are parallel: false for a similar reason that c) taking into account if they have the same direction or are opposed. .