A number of scientific studies have suggested that repeatedly heading a football could increase the risk of developing dementia   in later life. In 2002, former England international footballer Jeff Astle died aged 59. A coroner   said that Astle died from a brain disease likely to have been caused by "repeated small damages to the brain" related to heading a heavy leather football. Dr. Scott Delaney, research director of emergency medicine at McGill University Health Center in Montreal, Canada, has also researched soccer-related head injury and agrees that head-to-head or elbow-to-head blows are the real risk. In 2007, Delaney carried out a study on footballers aged between 12 and 17 that showed they were half as likely to be concussed   wearing headgear   than without. He said youngsters have a higher risk of head injury than adults because their heads are thinner and less able to absorb shock. To make matters worse, their neck muscles aren't as well developed and they often lack the correct heading technique that can help throw away the force of the ball. Delaney recommends that children wear headgear when playing football and says his two eldest children wear head protection playing the sport. But he admits that children can be unwilling to be the first to wear head protection--especially when their football heroes play without it. While headgear can protect footballers from being concussed during a match, no one knows the long-term effects of repeated "sub-concussive" blows to the head. Delaney says that while there is indirect evidence that a career in soccer can lead to dementia, no one has yet found a sure link between the two. He says proving a link would mean monitoring hundreds of footballers for three or four decades--and that would take a lot of funding. According to Delaney's research, what is the most risky injuries to head?
Long-term effects of blows. Wearing head protection. Underdeveloped neck muscles. Head-to-head or elbow-to-head blows.
Question: A number of scientific studies have suggested that repeatedly heading a football could increase the risk of developing dementia   in later life. In 2002, former England international footballer Jeff Astle died aged 59. A coroner   said that Astle died from a brain disease likely to have been caused by "repeated small damages to the brain" related to heading a heavy leather football. Dr. Scott Delaney, research director of emergency medicine at McGill University Health Center in Montreal, Canada, has also researched soccer-related head injury and agrees that head-to-head or elbow-to-head blows are the real risk. In 2007, Delaney carried out a study on footballers aged between 12 and 17 that showed they were half as likely to be concussed   wearing headgear   than without. He said youngsters have a higher risk of head injury than adults because their heads are thinner and less able to absorb shock. To make matters worse, their neck muscles aren't as well developed and they often lack the correct heading technique that can help throw away the force of the ball. Delaney recommends that children wear headgear when playing football and says his two eldest children wear head protection playing the sport. But he admits that children can be unwilling to be the first to wear head protection--especially when their football heroes play without it. While headgear can protect footballers from being concussed during a match, no one knows the long-term effects of repeated "sub-concussive" blows to the head. Delaney says that while there is indirect evidence that a career in soccer can lead to dementia, no one has yet found a sure link between the two. He says proving a link would mean monitoring hundreds of footballers for three or four decades--and that would take a lot of funding. According to Delaney's research, what is the most risky injuries to head?
A. Long-term effects of blows.
B. Wearing head protection.
C. Underdeveloped neck muscles.
D. Head-to-head or elbow-to-head blows.
Answer: