Is there a rule on the quality of football, and how to judge the quality of football?

"Jabulani" is derived from the African Zulu language, which means "universal celebration". The new match ball is a historic breakthrough in technology and has been designed with South African elements in mind.

Circumferential test of the sphere: FIFA approved qualifying standard: jabulani": - cm).

Durable Round Sphere Test: FIFA Approved Qualification Criteria: The maximum difference does not exceed. "jabulani": the maximum difference does not exceed .

Water Absorption Test: FIFA Approved Qualification Criteria: No more than 10% increase in the weight of the ball. "jabulani": sphere weight increased by 0 .

Weight test: FIFA approved qualifying standard: The weight of the football is between 420 445 grams. "Jabulani": weight 440 g (+ - 2 g).

Sphere shape and size retention test: FIFA approved passing criteria: 2,000 hits at 50 km/h "jabulani": 3,500 hits at 50 km/h.

**Performance test: FIFA approved passing standard: not more than 10 cm.

Ball pressure test: FIFA approved passing standard: ball pressure drop of no more than 20%. "Jabulani": The ball pressure drops by no more than 10%.

Not only weight and size, but also shape are specified.

Definitely. What's the use of a kick that blows up?

1. Look at the seams, sew from the inside to the outside, and the kind that can't see the threads on the outside is better.

2. Look at the weight and elasticity, the general No. 5 ball, that is, the standard game with the ball will be lighter, too light and heavy is not a good football, the elasticity will be very good, the sound of the bounce on the ground is also very thick, not as heavy as basketball, and not as brittle as volleyball.

3. Look at the appearance, the appearance is too smooth is not a good football, there must be a slight feeling of friction, it is the friction texture of the skin, not the appearance of the particles, floating point. The skin of the appearance will fall, it doesn't matter, the grass falls slowly, the artificial turf is second, the cement falls faster, it doesn't matter if the skin is off, but try not to play football in the water, it will fall very quickly after soaking.

Here's how to identify the quality of football:

Look at the seams: sew from the inside out, and the kind where you can't see the thread on the outside is better.

Look at the weight and elasticity: the general No. 5 ball is absolutely or, that is, the standard game ball, full of air will be lighter; Too light or too heavy is not good football; The elasticity will be good, and the sound of bouncing on the ground is also thick, not as heavy as basketball, and not as brittle as volleyball.

Look at the appearance: the appearance is too smooth is not a good football, there must be a slight feeling of friction, it is the friction texture of the skin, not the appearance of the particles, floating point. The skin of the appearance will fall, the grass will fall slowly, the artificial turf will be second, and the cement will fall faster.

It's okay to lose your skin, but try not to play soccer in the water.

After soaking, it will fall off very quickly.

The difference between b and the standard quality is minimal, and the quality is better

So the answer is: b

b is the least different from the standard reed quality before Zen annihilation, and the quality is better than that of He Qing

So the answer is: b